Sewing pieces of textile or other sheet materials dates back to the Stone Age if not before, and needles fashioned from bone are among man’s oldest tools. Until the nineteenth century, all forms of sewing were performed using the hands. Since then machines have gradually become available, and were popularised in the twentieth century, although a great deal of sewing is still done by hand. Across much of Europe and the Western world, sewing has traditionally been one of the key skills of women, although it has also been a professional task for men from sailors to surgeons. This article looks at those whose sewing goes beyond simply joining fabrics using thread, and tomorrow’s looks more broadly at sewing as an activity.

Although weaving has played an important role in several classical myths, sewing wasn’t as prominent. Even in Christian religious painting, it has only become a feature in more recent times.

In Dante Gabriel Rossetti’s early pre-Raphaelite painting of The Girlhood of Mary Virgin (1848–9), the young Mary is embroidering with her mother, Saint Anne, while her father, Saint Joachim, prunes a vine, by that time a thoroughly socially-acceptable activity for a gentleman. Rosetti uses Mary’s embroidery to introduce the symbolic colour red, signifying the Passion to come, and this slow, painstaking activity as a symbol of the demands of motherhood.

The most common narrative role of sewing in paintings is that of a woman supporting a cause or a person.

The patriot leader Giuseppe Garibaldi adopted the red shirt as an improvised uniform for his supporters, particularly the Garibaldini, who followed him in the Expedition of the Thousand of 1860, that led to unification of Italy. Odoardo Borrani’s Sewing Red Shirts for Volunteers (1863) shows four middle-class lady supporters eagerly doing their bit for Garibaldi’s cause.

In Edmund Blair Leighton’s Stitching the Standard from 1911, a young princess sits in a cutout at the top of a castle wall, sewing the black and gold flag to be flown from the castle. She comes straight from Arthurian legend, or a fairy tale, perhaps.

Eleanor Fortescue-Brickdale shows Elaine of Astolat in her illustration for the 1913 edition of Tennyson’s account of this story in his Idylls of the King. She sits sewing in the family castle, guarding Sir Lancelot’s shield.

Mothers, wives and daughters of fishermen provided their shoreside support, as shown by Anna Ancher in this Fisherman’s Wife Sewing from 1890.

Joaquín Sorolla’s Sewing the Sail from 1896 shows a scene on a patio at Valencia’s El Cabañal beach, during the Sorolla family holiday in the summer of that year. Although it may look a spontaneous study of the effects of dappled light, Sorolla composed this carefully with the aid of at least two drawings and a sketch. It shows the whole family engaged in one of the more technically challenging supporting tasks ashore.

Just as fishermen’s wives weren’t allowed to go to sea, other women sewing in supporting roles were also left behind. In the case of Wenzel Tornøe’s Seamstress, Whit Sunday Morning of 1882, that may not have been intentional. This seamstress had been engaged in making costumes to be worn for the Danish festivities of Pentecost (Whitsun), when many Danes rise early to go out and see the sun dance at dawn. By the time the festival morning has arrived, she has fallen asleep over her work, exhausted, with an oil lamp still lit beside her.

Harriet Backer’s Kone som syr (Woman Sewing) (1890) takes us back to more familiar daytime lighting, as a woman (a wife in the Norwegian title) sits at her sewing. This appears to have been a quick oil sketch, with its gestural depictions of potted plants, table, and chair, going beyond Impressionism.

If you want to run an older version of macOS that your Mac doesn’t support, so can’t boot into, then the only option is to run it within your current macOS. You may be able to do that using one of two methods: virtualisation or emulation. Emulation is normally used when the older macOS runs on a different processor, while virtualisation may be available when the processors share the same architecture.

Running Intel macOS

If you want to run a version of macOS for Intel processors, including Catalina and earlier, then your Apple silicon Mac has to run a software emulation of an Intel processor for that to work. Although this is possible using UTM, emulation is slow and not reliable enough to make this feasible for everyday use. It’s impressive but not practical at present. For an Apple silicon Mac, that automatically rules out running any macOS before Big Sur, the first version with support for Arm processors.

Rosetta 2 for Apple silicon Macs isn’t an emulator, although it allows you to run code built for Intel Macs on Apple silicon. It achieves that by translating the instructions in that code to those for the Arm cores in Apple silicon chips. This is highly effective and in most cases runs at near-native speed, but Rosetta 2 can’t be used to translate operating systems like macOS, so can’t help with running older macOS.

Virtualisation

Virtualisation is far more practical than emulation, as it doesn’t involve any translation, and most code in the virtualised operating system should run direct on your Mac’s CPU cores and GPU. What is required for virtualisation to work is driver support to handle access to devices such as storage, networks, keyboards and other input devices. Those enable apps running in macOS inside the virtual machine (VM), the guest, to use features of the host Mac.

Virtualisation of macOS, Windows and Linux have been relatively straightforward in the past on Intel Macs, as they’re essentially PCs, and providing driver support for guest operating systems has been feasible. That has changed fundamentally with Apple silicon chips, where every hardware device has its own driver unique to Apple, and undocumented. Without devoting huge resources to the project, it simply isn’t feasible for third-parties to develop their own virtualisation of macOS on Apple silicon.

Recognising this problem, Apple has adopted a solution that makes it simple to virtualise supported macOS (and Linux) using a system of Virtio drivers. Those have been progressively written into macOS so that it works both as a guest and host, for services that are supported by a Virtio driver, and all versions of macOS since Monterey have been able to virtualise Monterey and later when running on Apple silicon.

The drawback is that, although features supported by Virtio drivers are readily implemented in virtualisers, those that aren’t can’t be supported unless Apple builds a new Virtio driver into macOS. Even then, that new feature will only be available in that and later versions of macOS on both host and guest, as support is needed in both before it can work.

Another important consequence of virtualisation being built into macOS is that different virtualising apps all rely on the same features, and act as wrappers for macOS. While different apps may offer different sets of features and present them in their own interface, virtualisation is identical inside them. I’m not aware of any macOS virtualiser on Apple silicon that doesn’t use the API in macOS, and they all share its common limitations and strengths. This also means that, when there’s a bug in virtualisation within macOS, it affects all virtualisers equally.

macOS support

Early Virtio support appeared first in macOS Mojave and gathered pace through Catalina and Big Sur, but the first version of macOS to support virtualisation of macOS on Apple silicon Macs was Monterey 12.0. That means that no Mac released after the release of Monterey in the autumn/fall of 2021 will ever be able to run Big Sur, as their hardware isn’t supported by it, and macOS 11 can’t be virtualised. The only way to retain access to Big Sur is to keep an M1 Mac that shipped with it, the last of which was the iMac 24-inch M1 of 2021. However, it also means that the latest M4 Macs can run Monterey in a virtual machine, even though the oldest macOS they can boot into is Sequoia.

When the host or guest macOS is Monterey, sharing folders between them isn’t supported, and the only way to share is through network-based file sharing, which is less convenient. Display support was enhanced in Ventura, which again is required on both guest and host for it to be available.

Support for iCloud and iCloud Drive access didn’t become available in VMs until Sequoia, and now requires that both the guest and host must be running macOS 15.0 or later. As VMs that support these features are structurally different from earlier VMs, this also means those VMs that have been upgraded from an earlier macOS still can’t support iCloud or iCloud Drive. Only those built from the start to support Sequoia on a Sequoia host can support them.

Virtualisation can also have limited forward support, and is widely used to run beta-releases of the next version of macOS. This should be straightforward within the same major version, but testing betas for the next major version commonly requires the installation of additional support software. However, support for running betas is less reliable, and may require creation of a new VM rather than updating.

Many aren’t aware that Apple’s macOS licences do cover its use in VMs, in Section 2B(iii), where there’s a limit of two macOS VMs that can be running on a Mac at any time. This is enforced by macOS, and trying to launch a third will be blocked. For the record, the licence also limits the purposes of virtualisation to “(a) software development; (b) testing during software development; (c) using macOS Server; or (d) personal, non-commercial use.” It’s worth noting that Apple discontinued macOS Server on 21 April 2022, and it’s unsupported for any macOS more recent than Monterey.

Major limitations

The greatest remaining limitation in virtualising macOS on Apple silicon is its complete inability to run apps from the App Store, apart from Apple’s Pages, Numbers and Keynote, when copied across from the host. Even free apps obtained from the App Store can’t be run, although independently distributed apps are likely to be fully supported. This appears to be the result of Apple’s authorisation restrictions, and unless Apple rethinks and reengineers its store policies, it looks unlikely to change.

Some lesser features remain problems. For example, network connections from a VM are always treated as being Ethernet, and there’s no support for them as Wi-Fi. Audio also remains odd, and appears to be only partially supported. Although Sequoia has enabled support for storage devices, earlier macOS was confined to the VM’s disk image and shared folders. Trackpads don’t always work as smoothly as on the host, particularly in older versions of macOS.

Strengths

One of the most important features is full support for running Intel apps using Rosetta 2.

That and other performance is impressive. CPU core-intensive code runs at almost identical speed to that on the host. Geekbench 6 single-core performance is 99% that of the host, although multi-core performance is of course constrained by the number of cores allocated to the VM. Unlike most Intel virtualisers, macOS VMs attain GPU Metal performance only slightly less than the host, with Geekbench 6 Metal down slightly to 94% that of the host.

VMs are mobile between Macs, even when built to support iCloud and iCloud Drive access. Because each VM is effectively self-contained, this is an excellent way to provide access to a customised suite of software with its own settings. As disk images, storage in VMs is normally in sparse file format, so takes a lot less disk space than might be expected. It’s also quick and simple to duplicate a VM for testing, then to delete that duplicate, leaving the original untouched.

Future

Virtualising macOS on Apple silicon has relatively limited value at present, but in the future will become an essential feature for more users. Currently it’s most popular with developers who need to test against multiple versions of macOS, and with researchers, particularly in security, who can lock a VM down with its security protection disabled.

Few apps that ran in Big Sur or Monterey are no longer compatible with Sequoia. As macOS is upgraded and newer Macs are released, that will change, and virtualisation will be the only way of running those apps in the future, much as virtualisation on Intel Macs is for older macOS.

There will also come a time when Apple discontinues support for Rosetta 2 in the current macOS. When that happens, virtualisation will become the only way to run Intel apps on Apple silicon.

However, until App Store apps can run in VMs, for many the future of virtualisation will remain constrained.

Summary

macOS VMs on Apple silicon can:

• run Monterey and later on any model, but not Big Sur or Intel macOS;
• run most betas of the next release of macOS;
• run Intel apps using Rosetta 2;
• deliver near-normal CPU and GPU performance;
• access iCloud and iCloud Drive only when both host and guest are running Sequoia or later;
• but they can’t run any App Store apps except for Pages, Numbers and Keynote.

In a complete contrast to the death of Orpheus, the opening myth in Book Eleven of the Metamorphoses, Ovid continues with two lighter and humorous tales about King Midas.

Once Bacchus had turned the murderous Bacchantes into an oak wood, he left the scene and wandered to the River Pactolus. As was usual, the god was in the company of his friends, although Silenus was absent until he was retrieved by King Midas. To celebrate the return of Silenus, Bacchus invited the king to ask for whatever he wanted as a boon. Midas responded by wishing that everything he touched was turned to gold.

That wish was granted, and at first Midas was delighted and amazed with his new power. He turned a twig to gold, then a stone, a lump of earth, ears of wheat, and an apple. When he put his hands into running water, it too flowed gold. But when he tried to eat, the food he touched turned to gold before he could put it into his mouth, so too the wine that he was going to drink. Midas admitted to Bacchus how his boon was proving such a disaster, and pleaded for his power to be removed. Bacchus told him to go and wash his crime away in the headwaters of the River Pactolus, which coloured that river and its sands gold from contact with the king.

Walter Crane’s book illustration of King Midas with his Daughter, published in 1893, seems to be one of the few works telling this directly. It shows the hapless king, surrounded by all the gold objects he has touched, with his daughter dead on his knee, cold and gold.

Nicolas Poussin (probably) painted a remarkable and subtle work showing Midas Washing Himself in the Source of the Pactolus in 1627. Midas is almost out of sight at the left, but his touchmark gold is seen on the wreaths crowning the others present, and glowing on the nose of rock above them.

Having told us that unusual story in which one of the mortal characters performs all the transformations, albeit with the aid of a god, and accounting for natural gold in a river, Ovid moves on to the less known myth of Midas and a music contest. Despite similarities with that between Apollo and Marsyas, this has a humorous rather than gruesome ending.

Having developed a real loathing for riches, Midas led an outdoor life with the god Pan, but continued to do stupid things. Pan sang and played his pipes, making music he claimed was even better than that of the god Apollo, a boast that resulted in a contest between them, with Tmolus as the judge.

Pan played first, then Apollo, and inevitably Tmolus gave his verdict in favour of Apollo’s lyre, so Midas took exception to that, considering it unjust. Apollo responded by transforming the king’s ears into those of an ass, forcing him to hide them with a purple turban to spare him the laughter they caused. A servant who came to cut the king’s hair witnessed his secret, and told it to the earth in a hole that he dug. A grove grew where that hole had been, and when the south wind blew, the grove whispered the secret of the king’s ears.

Domenichino included The Judgement of Midas as part of the superb frescoes he and his workshop painted in the Villa Aldobrandini in 1616-18. Midas stands proud in his folly, his ass’s ears plain to see, with Apollo and Pan on each side. Amazingly, seven chalk drawings made for this have survived, and are in the British Royal Collection.

This jewel of a painting by Hendrick de Clerck, showing The Contest Between Apollo and Pan was painted in about 1620, just after Domenichino’s frescoes. Pan holds his pipes and dances at the right, and Apollo is seen bowing an early form of violin just to the left of centre. Between them are Tmolus, the judge next to Apollo, and Midas, with his ass’s ears. Seven Graces are also present, and Minerva is talking to Apollo.

A few years later Nicolas Poussin (probably) painted his version of Midas and Bacchus (1629-30), showing a different group. The centre trio are, from the left, Apollo, Pan (with his pipes), and King Midas, with fairly regular ears. At the far left, Bacchus has nodded off at the table, presumably from his customary excess of wine. In front could be Venus, perhaps, and there are sundry figures scattered, including two putti wrestling with a black and white goat.

Émile Lévy’s painting of The Judgement of Midas was completed in 1870, and is as clean and uncluttered as Crane’s later illustration. Apollo stands in disdain. Seated with his ass’s ears and a facile smile all over his face is King Midas, who is passing a gold laurel crown, a reference to his earlier golden touch, to Pan, who holds his pipes aloft in victory.

I hope that you enjoyed Saturday’s Mac Riddles, episode 291. Here are my solutions to them.

1: Lead-free stylus for early pros would have been ideal for Acontius.

Click for a solution

Apple Pencil

Lead-free (although a ‘pencil’ it has no lead) stylus (what it is) for early pros (announced on 9 September 2015 with the first iPad Pro, and works with early Pro models) would have been ideal for Acontius (who wrote an oath to bind Cydippe in marriage, see this article).

2: Eleventh vertical granite wall first took 47 days to climb, now less than four hours.

Click for a solution

El Capitan

Eleventh (OS X 10.11, released 30 September 2015) vertical granite wall (named after this 1 km wall of rock in Yosemite) first took 47 days to climb, now less than four hours (it took Warren Harding 47 days to climb it first in 1958, but can now be climbed freestyle in under 4 hours).

3: Rootless, I came in 2015 and still won’t go without csrutil.

Click for a solution

SIP

Rootless (an alternative name for System Integrity Protection), I came in 2015 (introduced in El Capitan) and still won’t go without csrutil (the command tool used to disable SIP).

The common factor

Click for a solution

They were all introduced in 2015, the year that this blog also started.

I look forward to your putting alternative cases.

One of the features of CPU cores in Apple silicon Macs is that they aren’t run at a single standard frequency or clock speed, but that varies depending on macOS. Moreover, those frequencies not only differ between generations, so aren’t the same in M2 chips as in the M1, but they also differ between variants within the same family. This article gives frequencies for each of the chips released to date, and considers how and why they differ. This has only been made possible by the many readers who generously gave their time to provide me with this information: thank you all.

The most reliable method of discovering which frequencies are available is using the command tool powermetrics. This lists frequencies for P and E cores, and this article assumes that those it gives are correct. Although it’s most likely that these frequencies aren’t baked into silicon, so could be changed, I’ve seen no evidence to suggest that Apple has done that in any release Mac.

Frequencies

If powermetrics is to be believed, then the maximum frequencies of each of the CPU cores used in each generation differ from some of those you’ll see quoted elsewhere. Correct values should be:

• M1 E 2064 MHz or 2.1 GHz; P 3228 MHz or 3.2 GHz;
• M2 E 2424 MHz or 2.4 GHz; P 3696 MHz or 3.7 GHz;
• M3 E 2748 MHz or 2.7 GHz; P 4056 MHz or 4.1 GHz;
• M4 E 2892 MHz or 2.9 GHz; P 4512 MHz or 4.5 GHz.

However, not all variants within a family can use those maximum frequencies. The full table of frequencies reported by powermetrics is:

This is available for download as a Numbers spreadsheet and in CSV format here: mxfreqs

Why those frequencies?

Depending on workload, thread Quality of Service, power mode, and thermal status, macOS sets the frequency for each cluster of CPU cores. Those used range between the minimum or idle, and the maximum, usually given as the core’s ‘clock speed’ and an indication of its maximum potential performance. In between those are as many as 17 intermediate frequencies giving cores great flexibility in performance, power and energy use. Core design and development uses sophisticated models to select idle and maximum frequencies, and undoubtedly to determine those in between.

Looking at the table, it would be easy to assume those numbers are chosen arbitrarily, but when expressed appropriately I think you can see there’s more to them. To look at frequency steps and the frequencies chosen for them, let me explain how I have converted raw frequencies to make them comparable.

First, I work out the steps as evenly spaced points along a line from 0.0, representing idle, to 1.0, representing the core’s maximum frequency. For each of those evenly spaced steps, I calculate a normalised frequency, as
(Fmax – Fstep)/(Fmax – Fidle)
where Fidle is the idle (lowest) frequency value, Fmax is the highest, and Fstep is the actual frequency set for that step.

For example, say a core has an idle frequency of 500 MHz, a maximum of 1,500 MHz, and only one step between those. Its steps will be 0.0, 0.5 and 1.0, and if the relationship is linear, then the frequency set by that intermediate step will be 1,000 MHz. If it’s greater than that, the relationship will be non-linear, tending to higher frequency for that step.

I’ll start with the E cores, as they’re simplest and have fewer steps.

E cores

For the M1, Apple didn’t try any tricks with the frequency of its E cores. There are just three intermediate steps, evenly spaced at 0.25, 0.5 and 0.75, and that’s the same with all E cores regardless of variant, from the base up to the Ultra.

With the M2, shown here in red, Apple added an extra step, and in the base M2 there’s also a lower idle frequency, not shown here. What is obvious is that those intermediate frequencies have been increased relative to those of the M1, turning the straight line into a curve.

The M3, shown here in blue, and M4, in purple, deviate even further from the line of the M1, with more steps and relatively higher frequencies.

This shows progress from the M1 in black to the M4 in purple, whose frequencies follow the polynomial shown.

Across the families, intermediate frequencies are most apparent in the E cores, where background threads are run at lower frequencies, and high-QoS threads that should have been run on P cores are run at higher frequencies. In M1 Pro and Max variants, with their two-core E clusters, macOS increases the E cluster frequency when they are running two threads to improve performance and compensate for their small cluster size.

P cores

With P core frequencies, the initial design for the M1 is different. The majority of the frequency steps follow a straight line still, but with a steeper gradient (1.23 against 1.00). Then in the upper quarter of the frequency range, above the step at 0.71, that line eases off to the maximum. This gives finer control of frequency over higher frequencies, and those higher frequencies are also reduced slightly in the base M1 compared to those here from the Pro, Max and Ultra.

In the M2 family, Apple divided frequencies into two: base and Pro variants have two less steps, with the base having a lower idle frequency. Shown here in red are those for the M2 Max, which are faired into a polynomial curve. That increases frequencies lower down, reduces them slightly at the upper end, then has a significantly higher maximum frequency.

Apple continued to tweak the P curves in the M3 (blue) and M4 (purple), with increasing numbers of steps but the same finer control at the upper end.

Here’s the comparison between M1 Max and M4 Max, with the same underlying ideas, but substantial differences. In the M4, each of the three variants released so far is different. The base M4 has a lower idle and maximum, the M4 Pro has a higher idle and maximum but one less step between them, and the M4 Max adds another step to the Pro’s series.

Significance

Apple’s engineers have clearly put considerable effort into picking optimised frequencies for each of the families and variants within them. If you still think that this is all fine detail and only the maximum frequencies count, then you might like to ponder why so much care has gone into selecting those intermediate frequencies, and how they’ve changed since the M1. Both P and E cores spend a lot of their time running at these carefully chosen frequencies.

In the first of these two articles visiting the Tuileries Gardens in central Paris, I showed paintings known to have been made before the Communards burned the Tuileries Palace in 1871, and those up to Monet’s views of 1876. As a result of damage to the palace, it was demolished in 1883, leaving the space it had occupied to become an extension to the garden.

Today the Tuileries retains two substantial buildings: the Jeu de Paume and Musée de l’Orangerie, both at the Place de la Concorde end and almost surrounded by terraces. Its broad Grande Allée joins the massive Arc de Triomphe with its smaller sister, the Arc de Triomphe de Carrousel, by the Louvre. Depending on the season, the gardens may be busy with runners, noisy with childrens’ amusements, or a well of relative calm amid the rumbling rush of Paris and its traffic.

Although Gaston de La Touche’s A Water Fountain in the Tuileries is undated, from its style it was painted after 1891, when he burned most of his earlier works and switched to this brighter style that could pass for Impressionism. Human figures are here, but dark, vague and subjugate to the jet of water in the fountain, the trees and the Louvre Palace behind. La Touche appears to have painted many fountains, and this may have been intended to form part of a series of such views.

Theodor von Hörmann’s undated In the Tuileries appears to be a brisk plein air sketch made in the late summer or early autumn. The child in the foreground is playing with a hoop.

The Tuileries Gardens, Paris (1895) may have been painted shortly before Maurice Brazil Prendergast left the city to return to Boston. While he was in Paris he met Édouard Vuillard, whose influence appears to have extended to his use of colour here, and Pierre Bonnard, an addicted sketcher of street scenes in Paris.

Childe Hassam’s Tuileries Gardens from about 1897 is an early work in Impressionist style, with visible facture and textbook linear perspective. Its gestural figures are skilfully executed, giving the viewer just sufficient detail to be able to distinguish different types of hats, for instance. This American Impressionist studied in Paris at the Académie Julian.

At the end of 1898, Camille Pissarro rented a flat for his family in Paris, from where he enjoyed a superb view over the Tuileries Gardens, which, unlike Monet and Renoir, he hadn’t painted until late in his career. His first series of eleven paintings was sold to Durand-Ruel in May for the sum of 27,000 Francs. The artist then returned to the same flat to paint a second series at the end of 1899.

These two versions of The Garden of the Tuileries on a Winter Afternoon (1899), above and below, are composed almost identically to Monet’s view from nearly 25 years earlier, with the dome of Les Invalides and the spires of the Church of Saint-Clotilde in the background. Pissarro was perhaps the first to capture the appearance of the gardens when busy, as they are during fine weather even in winter. His crowds of people are as varied and minimalist as those in his other series paintings of Paris.

Pissarro’s Garden of the Tuileries on a Spring Morning from the same year is a similar aerial view, this time well into springtime, with the trees in full leaf, in their brilliant fresh green foliage. Although there are fewer people now, Pissarro affords us some delicate detail, for instance in the pram just above the middle of the lower edge of the canvas.

There are subtle differences between these three canvases demonstrating that Pissarro’s painting was far from mechanical, and involved significant interpretation. The spring view has a lower skyline that cannot be accounted for by its being angled more to the left than the winter views, for example. However details of trees and even quite small features in the distance match well, supporting the view that he did remain faithful to the real world.

Judging by the brown foliage in the trees in The Tuileries Garden (1905), Pierre Bonnard painted this view in the autumn. The rich array of statuary stands out well.

The Tuileries Gardens (1910) is one of Jean-François Raffaëlli’s colour engravings of the gardens, in a formal view. It’s easy to see how Degas’ enthusiasm for Raffaëlli’s work to be included in Impressionist exhibitions was so divisive. Although popular at the time, it wasn’t in the least Impressionist, and now seems perhaps a little anachronistic.

Finally, Pierre Thévenet’s The Tuileries Gardens in Autumn from 1922 is unique among these paintings in being completely unpopulated, and shows some of the trees during leaf-fall, with their rich colours, and the Louvre in the background. Thévenet was a Belgian Post-Impressionist who lived and worked in Paris from 1919, painting many views of the city.

When Apple silicon Macs were first released, they brought a new secure boot process with a huge advantage over that of T2 Intel Macs: it was possible to boot them from an external disk without affecting their security. This is because all the crucial steps to secure boot processes are run from the Boot ROM and internal SSD.

The first snag with this was that hardly anyone was able to create a usable external boot disk for some months after those M1 Macs shipped. On 18 December 2020 I wrote here how I wished I could explain how to do that successfully, “but like many other M1 owners, all that I’ve tried so far has failed.” The only reader who reported that he had found the secret was Mike Bombich of Carbon Copy Cloner fame. Four days later, I had my first success, and wrote up the instructions, requiring a Thunderbolt 3 SSD connected to “one of your M1 Mac’s Thunderbolt ports”. However, trying to repeat that with a USB-C NVMe drive resulted in failure without apparent cause.

That article attracted a total of 109 comments, many of them from others who had tried, tried all sorts of workarounds, tried one last time, and still failed. By February 2021, the procedure remained as unreliable as ever, when I lamented that external boot disks still don’t work properly with M1 Macs. Among the comments are statements such as “It was no small task, took two months of messing around”. It wasn’t until the end of May, with Big Sur 11.4, that creating an external bootable disk came close to being reliable. I summarised the whole saga here.

The problems had certainly lessened, sufficient to consider what type of disk to boot from, but there were still inexplicable failures. Of note in that last link is the fact that all my successful tests had used the same Thunderbolt port on my Mac Studio. But why should we have noted which ports worked, and which were unreliable?

Since then, focus has shifted to matters of ownership and LocalPolicy, which have taken much of the blame for failures. Last week, when I was updating my instructions for creating bootable external disks, I happened to find Apple’s recent article on the subject.

This was the first time I had seen any warning of failures when the external disk is connected to the DFU port: “If you’re using a Mac with Apple silicon, plug your storage device into any compatible port except the DFU port. Find out how to identify the DFU port. Once the installation is completed, you can connect your storage device to any compatible port, including the DFU port.” That article was published on 1 October 2024, with a screenshot dating from macOS Sonoma.

Apple repeats that warning in its linked article on identifying the DFU port: “For certain tasks, such as reviving or restoring firmware or installing macOS on an external storage device, you need to know the location of your computer’s DFU (device firmware update) port.” That wasn’t published until 9 December 2024.

To understand why one of the USB-C ports on every Apple silicon Mac might be different, we need to go back to the start of its boot process, when it’s running from the Boot ROM and before that Mac has even got as far as its Low-Level Bootloader (LLB). One of the functions of its Boot ROM is to detect and if necessary engage DFU mode. To do that it has to initialise one of the USB-C ports, although it doesn’t do so with Thunderbolt support, which is why DFU connections are run using plain USB and not Thunderbolt. That’s done for simplicity, to keep the code in the Boot ROM to a minimum, and for more robust security.

That first port is designated as Bus 0 using Receptacle 1, which thus becomes the Mac’s DFU port. From the information so recently released by Apple, that port remains different, and when it comes to be used to create LocalPolicy for a bootable external disk, it fails. Thus if you try to install a bootable external disk through the DFU port, it’s doomed to fail.

Given that this limitation applies to all Apple silicon Macs, including those M1 models with Boot ROMs dating from 2020, and isn’t apparently limited to recent versions of macOS and their firmware, this appears to have been a problem all the way along, and at least a contributor to all those failed attempts to install bootable external disks, if not a primary cause. Since late 2020, and not disclosed until four years later.

Looking back at the comments made here at the time, these problems were sufficient deterrent to many who had been considering upgrading to Apple silicon at that time. When such an important feature of all previous Macs is at best tricky and unreliable, potential purchasers were understandably reluctant to pay for what was in so many other respects a triumph for Apple’s engineering teams.

I now look back on all those wasted days, weeks even, trying to get something to work that Apple must have known had a good chance of failing. Is it surprising that my sense of relief in finally learning one of the causes of all that wasted time and effort is overwhelmed with the anger that we’ve had to wait four years to be told one of the causes? And even now it’s hidden away in support notes that we only discover by accident.

If you have ever visited Paris, you will surely have walked in the Tuileries Gardens stretching from the Louvre to the Place de la Concorde and the Arc de Triomphe, on the bank of the River Seine, in the heart of the city, and where we visit this weekend.

With its origin as an ornamental Florentine garden for Catherine de Medicis’ Tuileries Palace in 1564, it has been open to the public for nearly 450 years. Over those centuries it has changed size and content. When the French Revolution started in 1789, it saw its fair share of bloodshed, and Jacques-Louis David the artist started to redevelop the gardens to his design.

By 1800, when Napoleon moved into the palace, it was used for an incongruous mixture of public promenade and relaxation, and military parades. On 23 May 1871 the palace buildings were burned by Communards in revolt; when the Tuileries Palace was finally demolished in 1883, the space that it had occupied was taken over as an extension to the gardens.

Today it retains two substantial buildings: the Jeu de Paume and Musée de l’Orangerie, both at the Place de la Concorde end and almost surrounded by terraces. Its broad Grande Allée joins the massive Arc de Triomphe with its smaller sister, the Arc de Triomphe de Carrousel, by the Louvre. Depending on the season, the gardens may be busy with runners, noisy with childrens’ amusements, or a well of relative calm amid the rumbling rush of Paris and its traffic.

The Rococo painter Jean-Antoine Watteau doesn’t appear to have painted the gardens themselves, but in Les Champs Élysées (c 1719) may show the gardens on the other side of what is now the Place de la Concorde.

The group of aristocrats feasting and cavorting in a luxuriant autumn landscape is typical of the sub-genre known as fête galante, showing the aristocracy outdoors at play, usually in mythological settings. These works were intended to circumvent the traditional order of merit of painting genres, which rated mythological and historical scenes highly, while allowing Watteau to paint images of the clients who paid for his paintings. It may have been that the title given to the painting was also a deliberate double entendre, covering both the earthly location and that in mythology: ‘the Elysian Fields’, the final resting place of the heroic and virtuous.

Jean-Baptiste Lallemand captured a defining moment at the start of the French Revolution in his Charge of the Prince of Lambesc in the Tuileries Gardens 12 July 1789, painted in 1789-90. His style and vocabulary owe much to Watteau and the earlier landscape masters such as Poussin, and show this bizarre combination of violence, panic, and normal routine, without so much as a drop of blood being spilled.

Jean-François Garneray’s watercolour showing The Duchesse de Berry and her children in their apartment at the Tuileries Palace was painted in 1822, and reveals the sumptuous interior of the palace before the Communards destroyed it.

Shortly before painting his most famous scene in the Tuileries, Édouard Manet completed a smaller and less ambitious work set in its trees, Children in the Tuileries Garden (c 1861-2).

Seen now as the work which gave him the idea for his second painting, this shows a small group of children apparently being directed by an older girl in black, with a blue bonnet. There’s an eery impersonality about the figures, though, as they’re either viewed from behind, or have little or no detail in their faces.

Manet’s Music in the Tuileries from 1862 is one of ten paintings shared between the National Gallery in London, and the Hugh Lane in Dublin, as part of the Hugh Lane bequest, and is currently in Dublin.

Packed into its rhythmic layout of trees are members of the fashionable Parisian crowd, who have come to listen to the music, socialise, and chat. Historians have identified many of Manet’s circle among them: the poet Baudelaire, novelist Gautier, composer Offenbach, Fantin-Latour the painter, and the artist’s brother Eugène, a painter who married Berthe Morisot, the Impressionist.

Adolph Menzel’s Afternoon in the Tuileries Gardens from 1867 is assumed to have been inspired by Manet’s Music in the Tuileries, and has compositional similarities. He includes some direct quotations of figures in homage to Manet’s work. However, Menzel remained a realist, as shown in finely detailed foliage, foreground shadows and the figures. He was known to have made several sketches in the Tuileries Gardens, but painted this work back in his Berlin studio. Conventionally this would have been based on those sketches, but when Menzel first showed the work he claimed it was executed from memory.

Stanislas Lépine’s Nuns and Schoolgirls in the Tuileries Gardens, Paris from 1871-3 is unusually dark and Barbizon School in style. The nuns and girls are shown emerging from the burnt-out shell of the Tuileries Palace, after the Paris Commune of 1871. The contrast between this sombre group of modestly-dressed figures and previous depictions of the gardens is interesting, and may reflect the spirit of the day in Paris, after the Commune was crushed but before Haussmann’s major reconstruction of the city. Lépine was a pupil of Corot who mostly painted views of Paris in Corot’s style.

Claude Monet painted the Tuileries in four works from about 1876.

Tuileries (study) (1876) is one of two studies that he subsequently signed and dated incorrectly to 1875. This and the finished work below were painted from the top of 198 Rue de Rivoli, where his friend Victor Choquet lived. In the background is the dome of Les Invalides and the spires of the Church of Saint-Clotilde.

Tuileries (1876), one of Monet’s two finished works, shows a different view from the same vantage point, for which no studies remain. Wildenstein tells us that this painting was used by Émile Zola in his novel l’Œuvre, as a painting by the hero Claude Lantier of a corner of the Place du Carousel. As is often the case with Monet’s paintings, what appears to be a brisk and spontaneous plein air has many brushstrokes that were applied wet on dry, indicating he worked on this painting in the studio over a period of several days or more. Although figures are gestural, they and the foliage include fine marks and subtle details.

Here are this weekend’s Mac riddles to entertain you through family time, shopping and recreation. This week they celebrate the tenth anniversary of the start of this blog, on 17 January 2015.

1: Lead-free stylus for early pros would have been ideal for Acontius.

2: Eleventh vertical granite wall first took 47 days to climb, now less than four hours.

3: Rootless, I came in 2015 and still won’t go without csrutil.

To help you cross-check your solutions, or confuse you further, there’s a common factor between them.

I’ll post my solutions first thing on Monday morning.

Please don’t post your solutions as comments here: it spoils it for others.

It might seem strange today, but for much of the early history of the Mac we used printed manuals and books. For developers the reference was Apple’s Inside Macintosh series, lovingly crafted by its technical authors using Microsoft Word and published by Addison-Wesley. Even Aperture (2005) and Apple’s Pro apps like DVD Studio Pro 3 (2004) came with beautifully prepared and printed manuals.

It was the introduction of Apple’s first CD-ROM drive in 1988 and its subsequent release of the first developer CD, Phil and Dave’s Excellent CD the following year that started change. At first there was a battle between nascent common document formats, including Adobe’s Acrobat, Farallon Replica, DjVu and others. In the early 1990s this led to HTML-based help books, and printed manuals became gradually replaced by electronic documentation.

Unix had a longer evolution, with the first of many man pages written for formatting using nroff in 1971. Although printed references were published later, deep piles of fanfold printout remained popular long after the rest of computing had discovered the value of desktop publishing. While much reference material was still confined to source code files, brief glimpses into how to use commands are still revealed in lightly formatted text man pages.

The release of Mac OS X 10.0 brought with it a primary help system, Apple Help, as part of Cocoa. Those creating help books wrote them in HTML saved in a folder structure like a local website, and a cut-down browser Help Viewer displayed them for the user. The only detailed account of this, the Apple Help Programming Guide, was first published in 2003, and last revised a decade later, 12 years ago.

Help Viewer started with a spartan interface, here in 2004, and relied primarily on pages stored in local help books.

Help books can contain localised versions to support their use worldwide.

Although seldom used, you could build your own custom help book, as shown in this demonstration I created for the UK magazine MacUser in 2006.

Apple reserved /Library/Documentation/Help and its sibling in the user’s Home library for its own use, and from OS X 10.6 third-party help books were expected to be stored as a .help bundle in the Resources folder in an app’s bundle. HelpViewer.app was hidden away in /System/Library/CoreServices, and helpd was an on-demand service to watch Applications and Utilities folders for newly-added apps containing help bundles, and register them with macOS.

By 2017, HelpViewer’s toolbar offered Back and Forward buttons, a button to hide or show the sidebar, and one to share the current page.

Searching help was aided by an index built by Help Indexer during authoring (below, from 2006), and used Spotlight’s local search powers.

Unfortunately, help became neglected and started to deteriorate. During macOS High Sierra 10.13 to 10.13.4, it was revised internally, and the way that helpd worked was improved.

The macOS help system had previously relied on the user (or an installer) adding an app bundle to one of its two watched folders, /Applications and /Applications/Utilities, to trigger the process of adding any new or updated help book to those available. The helpd service was activated by File System Events when such an event occurred, and responded by checking the app bundle for a help book to register it. If an app was installed in another folder, even ~/Applications, then its help book might not get registered properly.

Identification of help books also changed. Previously, that for the Dictionary app was known as com.apple.Dictionary.help, making it difficult to accommodate more than one version of an app and its help book at a time. The new system incorporated a version number, such as com.apple.Dictionary.help*2.2.2.

When originally developed, the great majority of help books relied on static content built into them. All that had to happen for most was the launch of HelpViewer, and for it to open the supplied Help book.

Since then, help books had increasingly relied on online content, which needed to be refreshed before each access. Thus HelpViewer and helpd had to work together to deliver the latest content, with helpd doing the refreshing and updating to the databases in ~/Library/Caches/com.apple.helpd, which HelpViewer used with the WebCore rendering engine to display pages and interact with the user.

Since then further bugs have come and gone; among the more troublesome were those in Big Sur and Monterey, that could prevent a Help book from opening, or, if it did eventually open, the book displayed completely blank pages.

It also had some more amusing moments, including a phase in which the help system decided that I wanted to read Apple Configurator’s help book in French.

For Ventura, Apple revised the help system further, and renamed HelpViewer to Tips while keeping its formal identifier as com.apple.helpviewer, and it remained hidden away in CoreServices. In Sequoia, it leapt from version 10 to 15 and joined Apple’s first league apps between Time Machine and TV in the main Applications folder. But if you want to read the documentation for any command tool, you still have to refer to its man page.

Over the last four months, I have posted a series of twenty articles about paintings showing rural life in Europe between 1500 and the 1920s. At the start of that period, countries across Europe were overwhelmingly rural, with about 80% of their people living in the countryside and engaged almost entirely in agricultural work. By the end of the nineteenth century that had reversed, with 80% living and working in cities and towns. This new series looks at where all those people went to live and work, the towns and cities, and what happened to them there.

Cities are of ancient origin. In its heyday, the city of Babylon had a population exceeding 200,000 and covered an area of about 3.5 square miles. Paris, the largest city in Europe in the early fourteenth century, had only just reached that size, and even now modern Paris has only ten times the population it had in 1328. By 1780, Paris had trebled in size, to a population of 650,000, and its accelerated growth during the nineteenth century saw it grow to 2.7 million in 1901.

Conventional wisdom holds that the size of cities is primarily limited by the population required to remain in the country to produce food for those in the city, and the city’s limited employment prospects. The first was changed dramatically by the ‘Agricultural Revolution’, and the second by the ‘Industrial Revolution’. As we saw in the previous series, there wasn’t any discrete revolution in agriculture, but a prolonged series of improvements in yield. The Industrial Revolution started in rural areas, close to sources of its raw materials such as coal for energy and ores for the production of metal.

Cities were also vulnerable to depopulation, as the result of destruction in war, natural disasters, and epidemics including the Black Death and other outbreaks of plague, cholera and other infectious diseases that swept Europe from the Middle Ages until the twentieth century. They were also dependent on reliable supplies of food, and years with bad harvests could have significant impact on the growth of cities, even when they had a range of supply areas and good food security.

Nevertheless, with improvements in agriculture and the rise of manufacturing industry in the eighteenth and nineteenth centuries, towns and cities across Europe grew by attracting people from the country, and by their own increasing birth rate.

The lure of city life is well summarised in Jean Béraud’s fashionably-dressed Milliner on the Champs Elysées. This was all about the promise of material goods and wealth, fine clothes, and smart carriages, all the things that were lacking in rural life.

Artists like William Hogarth had been moralising about the dangers of this since the early eighteenth century, in visual stories such as his Harlot’s Progress.

Its general outline is of an innocent country girl, Moll Hackabout, who comes to London, and immediately falls into the hands of a notorious brothel-keeper and madame. Moll becomes the kept mistress of a wealthy merchant, but later slides into common prostitution. She’s arrested, and ends up in London’s Bridewell Prison. Having earlier contracted syphilis, that disease progresses, steadily killing her. She finally dies at the age of 23, mourned only by her fellow prostitutes.

Moll Hackabout is first shown arriving at the Bell Inn, Cheapside, dressed in the fine bonnet and white dress of an innocent country girl. She’s seen being inspected by Elizabeth Needham, a notorious brothel-keeper and madame. Hogarth gives the latter black skin lesions as a mark of longstanding syphilis, and her face is aged.

In the doorway at the right is an equally notorious rake, Colonel Francis Charteris, and his pimp John Gourlay, who are also taking an interest in the arrival of a fresh young innocent. In Moll’s luggage is a symbolic dead goose, suggesting her eventual death from gullibility. The address on the label attached to the dead goose reads “My lofing cosen in Tems Stret in London”, implying that Moll’s move to London has been arranged through intermediaries, who will have profited from her being trafficked into the hands of Elizabeth Needham.

Behind Moll, an itinerant preacher is engrossed in spreading the message to his small ad hoc congregation in the back of a covered wagon. In front of that a pile of pots is just about to collapse, as is Moll’s life.

I’m sure those prospects weren’t in the minds of Erik Henningsen’s Farmers in the Capital (1887) when this country family first arrived in Copenhagen, complete with their large chest and farm dog. Around them city-dwellers are dressed fashionably, and stare at the outsiders with their rough clothing and filthy wooden clogs.

What these migrants found was different from the stories they had heard.

Frits Thaulow’s The Smoke from 1898 shows a suburb overwhelmed by the smoke, with houses crammed up against the factory walls. Few cities enforced any separation between industrial areas and housing, and there weren’t restrictions on the discharge of smoke even in densely populated zones. The water surface is also grimy and lacks the artist’s distinctive intricate reflections.

Children found their work very different from that in the country. Instead of looking after livestock and gleaning, they found themselves working long hours in demanding and often hazardous surroundings.

Joan Planella i Rodríguez’ The Little Weaver (1882-89) is a superb Naturalist painting with strong social content. This is a replica of the artist’s original completed in 1882. It shows a young girl working at a large and complex loom in Catalonia, as a man lurks in the background, keeping a watch over her. Machinery had no safety guards, and industrial accidents were commonplace.

Oslo, like other major Nordic cities, was small by comparison with Paris, and even in 1900 had a population of just 230,000, about the same size as Babylon at its height. Yet its growth in the nineteenth century was concerning many, including the artist and writer Christian Krohg.

His Tired from 1885 was part of a longer-term exploration of the theme of fatigue and sleep, particularly among mothers. The young woman seen here is no mother, but a seamstress, one of the many thousands who worked at home at that time, toiling for long hours by lamplight for a pittance. At the left is an empty cup, which had probably contained the coffee she drank to try to stay awake at her work.

Home work as a seamstress was seen at this time as the beginning of the descent into prostitution, a major theme in Krohg’s work. The paltry income generated by sewing quickly proved insufficient, and women sought alternatives, which all too often led to prostitution. During the 1880s, therefore, in some countries in Europe, the sewing machine was seen as a precursor to a woman’s moral downfall, the top of the slippery slope.

Just before Christmas 1886, Krohg’s first novel Albertine was published by a left-wing publisher. Its central theme is prostitution in Norway at the time, and the police quickly seized all the copies they could find, banning it on the grounds of violating the good morals of the people. At the same time as he was writing that novel, Krohg had been working on his largest and most complex painting: Albertine in the Police Doctor’s Waiting Room (1885-87).

In the novel, Albertine starts as a poor seamstress, who is mistaken for a prostitute by the police officer in charge of the section controlling prostitutes. He plies her with alcohol, then rapes her. She is summoned to be inspected by the police doctor, whose examination further violates her, making her think that she is destined to be a prostitute, and that’s exactly what happens.

Albertine is not the prominent woman in the centre looking directly at the viewer. Krohg’s heroine is the simple and humble country girl at the front of the queue to go into the police doctor for inspection. Behind her is a mottley line of women from a wide range of situations. At the right, in the corner of the room, is another country girl with flushed cheeks. Others are apparently more advanced in their careers, and stare at Albertine, whose profiled face is barely visible from behind her headscarf. Barring the way to the surgery door, and in control of the proceedings, is a policeman.

Most of those who moved into the cities left relatives behind. Although their homes in the country may have been primitive, they realised that in the city they needed a constant supply of money to avoid falling into debt and risking eviction.

This family of four has just been Evicted, as shown by Erik Henningsen in 1892. With them in the snowy street are their meagre possessions, including a saw implying the father is a carpenter. In the background he is still arguing with a policeman.

For every young woman who succeeded as a fashionable milliner, there must have been thousands who became trapped in prolonged, exhausting labour, and a few who lost everything.

This young mother and child in Arturo Michelena’s Charity from 1888 have shacked up in a hovel. A pair of bourgeois ladies have arrived to do their bit for charity, without which the mother and child would have starved and died of disease.

In the coming weeks and months, I aim to bring paintings of the reality of life for urban revolutionaries of the eighteenth and nineteenth centuries. I hope you will join me.

Since Apple released the first M1 Macs over four years ago, I’ve been guilty of making the assumption that P and E cores used in the variants (base, Pro, Max and Ultra) in each family are identical. Thanks to the persistence of Thomas, I have learned the error of my ways and can now tell you that, while their hardware might be the same, there’s at least one significant difference between some, their operating frequencies, or clock speeds.

This all came to light when I claimed that the E cores in M4 family chips have a maximum frequency of 2,592 MHz, and Thomas tried to correct me by informing me that his have a maximum of 2,892 MHz, a substantial 300 MHz greater. His are in a base M4, mine in an M4 Pro, which seems even stranger, as the trend is for faster CPUs to run at higher frequencies, and that’s true when you compare their P cores: his can only rise to 4,462 MHz, while mine are slightly faster at 4,512 MHz.

The lesson is learned: E and P cores within the same family can have different operating frequencies. Going back to look at my records of the M1 family, I then realised that, while their E cores have identical frequencies, the P core maximum in a base variant is 3,204 MHz, while Pro and Max variants can run up to 3,228 MHz. Although that difference of only 24 MHz is far less, it can’t have occurred by accident.

The purpose of this article is to show the core frequencies that I have already measured [, and ask for your help in filling in the blanks in this table – no longer required, thank you]

Frequency table

The only variant I was missing from those in the M1 family is the M1 Ultra.

I didn’t have any M2 Macs at all, as we decided to skip them and our only M2 chip is in my wife’s iPad Pro. I now have all four, thank you.

I only had one in the M3 family, the M3 Pro in my MacBook Pro, but have all of them now.

Thanks to Thomas, I already have two from the M4 family, the base and Pro variants, and I now have an M4 Max completing these before the Ultra comes later this year.

How to report frequencies

If you’re able to add to this collection, please open Terminal and run the command
sudo powermetrics -n 1 -s cpu_power
which then prompts you for your admin password. A few seconds later the window will fill with a single set of measurements looking like this:

All I’d like is a copy containing 3 lines from that:

• Machine model at the top, to tell me which Mac it is, thus which chip.
• E-Cluster HW active residency, which contains a list of frequencies for the E cores.
• P-Cluster HW active residency, which contains a longer list of frequencies for the P cores.

To help, I have highlighted those three lines in the screenshot above.

I now have all the frequency sets that I needed to complete the table.

Reward

I have added your entries to my Numbers spreadsheet, and will make that available for free download from here, so anyone who wants to check those frequencies can do so.

Frequency information also builds our understanding of Apple silicon chips. My next questions are going to be why there are those differences, and whether they significantly affect the performance of our Macs.

Thank you for helping, and thanks to Thomas for demonstrating that CPU cores of the same type aren’t the same after all.

Postscript

Thank you to all who responded so quickly. I now have all the frequencies and no longer require any more, thank you. I will post an updated table with a brief analysis on Monday. There are a lot of differences, many of them surprisingly subtle!

In this second selection of interiors painted by Pierre Bonnard (1867-1947), I concentrate as he did on the intimate domestic life of his partner, later wife, Marthe. This came to obsess him during the twentieth century, to the point where he not only sketched and painted her constantly, but amassed thousands of photographs, the majority of them showing her at her toilet, and in her bath. Marthe apparently had a medical condition that made frequent long periods in the bath relieving, and Bonnard took every opportunity to paint her there.

By 1908, his intimate visual diary of Marthe’s life was becoming the focus of his development and innovation. In El Tocador, which means The Dressing Table, Marthe’s headless torso is seen only in reflection. The direct view is of the large bowl and pitcher she used to wash herself.

Mirror in the Dressing Room (1908) shows a similar dressing table and mirror, but in contrasting blue decor. A woman’s nude back and buttocks now appear in the mirror, as another young woman sits at the left drinking a cup of coffee.

Of all these works Bonnard painted in 1908, my favourite is The Bathroom, or The Dressing Room with Pink Sofa, which anticipates those from later in his career, painted when Bonnard was living in the south of France. Looking at a brightly lit window from a slightly elevated position, Marthe’s body is seen against that light, and the bright colours of the room.

There is subtle mirror-play, with her headless torso shown in the dressing table mirror, in which the artist is replaced by an empty chair. Its last reflection is that of the window frame in the residual water in the shallow metal bath at the left.

Among his intimate domestic scenes, Reflection or The Tub (1909) is one of his best pieces of mirror-play. He again opts for the view from an elevated position, looking down and into an angled plane mirror in the bathroom. The reflected view almost fills his canvas, with the nude Marthe (I think) crouching slightly in the upper left corner, as she dries herself after a bath.

The angle of view plays some odd tricks. The washing bowl on the dressing table is brought to overlie the larger shallow bathtub on the floor, for example. Some of the objects on the dressing table are shown directly, others only in the reflected image. And over on the opposite side of the room is a chair, and a coffee tray.

Four years later, Bonnard hadn’t abandoned his mirror play, nor removed his easel from more private rooms in the house. The Dressing Table with a Bunch of Red and Yellow Flowers (1913) presents us with another visual riddle that we struggle to resolve. Shown in the mirror above the dressing table is a reflection of what lies behind the artist. There’s a nearly nude figure sat in the corner, and what appears to be a bath, or a bed on which there is a large black object, possibly a dog. As ever, the artist is nowhere to be seen, unless of course that headless figure is male rather than female.

The following year, Bonnard moved back from the dressing table and its mirror, for The Bathroom Mirror (1914). Marthe’s reflection is now but a small image within the image, showing her sat on the side of the bed, with a bedspread matching the red floral pattern of the drapes around the dressing table. Bonnard has worked his usual vanishing trick for himself, and a vertical mirror at the right adds a curiously dark reflection of the room.

Nude in an Interior from about 1912-14 refers back to his Man and Woman in an Interior from 1898, with such extreme cropping that only a thin sliver of Marthe is visible. Something else is in front of her, perhaps the artist or a hanging dress, but so little of it is shown that it is unidentifiable. The rest of the interior is a complex overlay of coloured rectangles, from cropped surfaces and objects. We feel as if we have caught a glimpse of something that we shouldn’t have, but remain fascinated in trying to imagine what we cannot see.

Bonnard’s best-known nudes of 1925 are those where his model is still in the bath, most notably Nu dans la baignoire, or Nude in the Bath. The bath is cropped to show just the lower torso and legs of the woman in its water. A second, clothed, person is striding across from the left, its figure cropped extremely to show just the front of the body and legs.

It’s thought that the figure on the left is that of the artist, but I cannot make sense of that. He or she appears to be wearing light patterned clothing consisting of a jacket and long skirt, with soft slippers resembling ballet shoes!

This is a marked contrast from Bonnard’s recent nudes in returning to intimate scenes of everyday life, with a strongly voyeuristic sense of peering into private life. It isn’t known whether Bonnard painted this before his lover Renée Monchaty committed suicide in a bath, although his bathing paintings from 1925 onwards are often supposed to refer to her death.

Of the surviving paintings from the 1930s that I have been able to locate, intimate domestic scenes and nude figures again predominate. The Toilette (Nude at the Mirror) (1931) is another piece of mirror-play that departs from his earlier practice: the nude stands in front of the mirror, but she isn’t seen in reflection at all, only directly. Instead, the mirror reinforces the verticals of the window and curtain off to the right.

Nude by the Bathtub (1931) shows Marthe leaning idly against a deep bathtub. She appears to be surrounded by frosted glass, which on the right resembles the foam of a breaking wave.

Marthe and much of the rest of Bonnard’s Nude in Bathroom (Cabinet de Toilette) from 1932 have become shockingly pink. Even her dog, sat by her feet, is strongly red-brown. Bonnard has returned to the Nabi style of not projecting the patterning of the floor according to perspective, flattening the lower third of the painting.

Nude in Bathtub (c 1938-41) is perhaps the culmination of the changes that had been taking place in Bonnard’s painting. Its colours are brilliant and visionary. The form of the bath adopts itself to that of Marthe within, curving around her legs in its asymmetry. The shimmering patterns of the floor and the curtain are independent of their orientation. Beside the bath, Marthe’s dog looks up at the viewer, as if knowing where this is all heading. On 26 January 1942, Marthe Bonnard died in their villa at Le Cannet.

Here are this weekend’s Mac riddles to entertain you through family time, shopping and recreation.

1: Quiet kip to extend endurance is better tight than rough.

2: Brief doze while working on intel only.

3: Winter dormancy is a pmset mode.

To help you cross-check your solutions, or confuse you further, there’s a common factor between them.

I’ll post my solutions first thing on Monday morning.

Please don’t post your solutions as comments here: it spoils it for others.

Twenty years ago today, on 11 January 2005, Apple introduced its first Mac mini at MacWorld Expo in San Francisco, and eleven days later the first were delivered to eager customers. This article celebrates Apple’s only highly successful low-cost compact Mac.

From the first 128K Macintosh 41 years ago, Apple’s Macs have been premium products. That first Mac cost $2,495, despite being claimed to be affordable, and subsequent models did little to attract those buying cheaper PCs. The Macintosh II of 1987 was the first model with a separate display, but that was even more expensive, starting at $3,898.

Apple’s next idea of low cost came in the Macintosh LC starting at $2,400, and its LC successors, but none captured the market they were aimed at. The iMac from 1998 was far more successful, but kept to the original Mac’s concept of an integral display.

On 11 January 2005, Steve Jobs was reported as saying: “Starting at just $499, Mac mini is the most affordable way to enjoy Mac OS X and iLife. Just plug in your display, keyboard and mouse and you’ve got an incredibly compact Mac for a price that almost anyone can afford.” They started shipping in the US on 22 January, and a week later across the rest of the world.

That was the heyday of the Power Mac, and that first Mac mini came with a choice between 1.25 and 1.42 GHz PowerPC G4 processors, starting at $499 and $599 respectively. Build-to-order options could expand it to a total of 1 GB memory, with an optical SuperDrive, AirPort Extreme Wi-Fi card, internal Bluetooth, keyboard and mouse.

There were two revisions of that model in 2005, before it was replaced in February 2006 with the first Intel Mac mini. Here Apple made a small but historical slip in offering a base model with a single-core Yonah processor, making it the only single-core Intel Mac ever sold. That was soon rectified when all Mac minis came with Intel Core 2 Duo processors.

Because of their low cost, size and lack of display, Mac minis became popular as servers that could be tucked away out of sight. In October 2009, Apple released the first Mac mini Server, complete with a copy of Mac OS X Server. These early models also had the benefit of using socketed CPUs, so could be upgraded with more recent and faster processors.

Mac mini Late 2009 (2009). Image by Fletcher6, via Wikimedia Commons.

This Mac mini from late 2009 is the last of the original design, and shows how well-equipped it came in terms of ports. In the top row, from left to right, are the power button, ventilation holes, Kensington lock slot, audio in, and audio out. Along the bottom row are DC power input for its external power supply, Gigabit Ethernet, FireWire 800, Mini DVI, Mini DisplayPort, and its five USB 2.0 ports.

The Mac mini’s first redesign followed, and the new, thinner and more compact aluminium Unibody mini was released in June 2010.

Mac mini Mid-2010 (2010). Image by Manu zoli, via Wikimedia Commons.

This Unibody model from mid 2010 shows the new generation of ports, including RJ-45 Gigabit Ethernet, FireWire 800, HDMI and Mini DisplayPort, four USB 480 Mb/s, SD card slot, analogue/optical audio input, and analogue/optical audio output. Significantly, its power supply was now internal.

The following year, this was revised to bring support for Thunderbolt 1, but the internal optical drive was removed.

Since then, the Mac mini has remained highly popular, and has thrived with faster and more capable Intel processors. It has been packed into special rack and other mounts for mini server suites and Internet hosting, and taken far beyond the original concept of an affordable compact Mac. In 2018, the range included 4- or 6-core Intel Core i3, i5 or i7 processors that continued to be sold until two years ago, making the Mac mini one of the last Intel Macs.

The first Apple silicon Mac mini was released in late 2020, and came with the base M1 chip and no option for anything more powerful. That was rectified in January 2023, when the next Mac mini offered a choice between the base M2 and M2 Pro chips. However, Apple didn’t offer a Mac mini with an M3 chip, instead skipping straight on to the M4 and M4 Pro on 29 October 2024 in a surprise new design that shrinks its size even further.

Despite the popularity of Mac minis over those years, critics seldom gave it the praise it deserved, until the first Apple silicon model. The mini has served in almost every environment, and for most purposes. Those include home servers, home theatre and media libraries, and in sectors such as small business and education. It’s also being used by several cloud and colocation services, including MacStadium. Only with the latest higher-powered M4 variants has the Mac mini finally come of age in delivering the performance desired by many previous purchasers.

We look forward to the next twenty years of the Mac mini, Apple’s highly successful low-cost compact Mac.

References

Original press release, at the Internet Archive
Wikipedia

Pierre Bonnard (1867-1947) was a relative latecomer to interiors, and throughout his career he was a prolific painter of the outdoors. However, when he started living with Marthe, he began to paint her almost obsessively, and took thousands of photographs of her. In these two articles I have selected some of those works that best fit the new genre of interiors, starting here with various rooms, and concluding tomorrow in Marthe’s bathroom.

In 1898, Bonnard painted the first of his controversial works revealing his private life with Marthe, in Man and Woman in an Interior, a motif known better from his later version of 1900. He stands naked, looking away, as Marthe is getting dressed on the bed. Its post-coital implications are clear. The image has also been cropped unusually, as if it was a ‘candid’ photo, enhancing its voyeuristic appearance.

In Bonnard’s Young Woman by the Lamp (1900), the artist explores a different light, cast by table lamps. In the foreground a woman is busy sewing under the lamp’s glow. In the background, at the left, a couple sit by another table lamp with a green shade.

In the early years of the twentieth century, Bonnard used mirrors and reflections in several paintings, including this Interior from about 1905. It’s an unusual composition, with just a little of the woman’s back visible in the mirror; Bonnard instead shows the reflection of a chair placed in front of the mirror, and what appears to be the artist sat at a table.

His purpose in placing the chair in front of the mirror was, I think, to demonstrate that the artist’s eye is in line with the chair and with his own reflection, confirming that it is him who is sat at the table, although he doesn’t have an easel, neither is any canvas or palette visible.

The Milliner, painted in 1907, features Anita Champagne’s distinctive chignon. The hat she has brought is laid carefully on a chair beside her.

Bonnard’s sister and her family were one of his favourite motifs. In The Claude Terrasse Family from 1908-10, the artist again looks at the play of lamps and their light, although he curiously manages to avoid showing any face. Claude Terrasse the musician and composer is naturally at his piano, his face obscured by a lamp standing on its corner. Bonnard’s sister and her daughter sit sewing at the table, lit by a larger lamp and facing away.

Bonnard’s private life was ever turbulent. In Before Dinner (1924), there are two places laid at the table, and two women behind. One at the left has her back towards the other, who stands by the table as if waiting for something to happen. A dog is just emerging from behind the chair at the left, and looks up the standing woman.

The Table (1925) presumably shows Marthe eating at a table replete with fruit and other food.

At first sight, White Interior from 1932 looks deserted. Outside it is late dusk, and the cool breeze has started to blow in from the balcony, through the open French windows. The table is busy, and on the far side of it is Marthe, almost blending in with the carpet. Interior white surfaces, including the door and a radiator, are brilliant in the harsh electric light.

Villa Bosquet, Le Cannet, Morning from about 1945 is Bonnard’s strongest statement of his loneliness at home after Marthe’s death. The empty chair at the table and its even areas of paint are a marked contrast to his earlier domestic views.

Interior: Dining Room is claimed to date between 1942-46. It’s dark outside. On the table inside Le Bosquet, there are bowls of fruit laid out, and at the right a blonde woman sits to eat.

Macs use two main features to safeguard your data when it’s stored locally: encryption using FileVault, and APFS encrypted volumes. Although they might appear to be the same, this article explains how they differ, particularly on Macs with T2 or Apple silicon chips.

Definitions

FileVault is a form of encryption applied to the whole contents of the Data volume in a macOS boot volume group, controlled through the FileVault entry in Privacy & Security settings, and its predecessors.

An APFS encrypted volume is any volume (outside the Data volume) that is formatted using APFS Encrypted, either when first created or subsequently using the Finder’s contextual menu command, or an equivalent.

Enabling FileVault

FileVault is enabled and disabled using its entry in Privacy & Security settings, and applies only to the Data volume in the currently active boot volume group.

When you enable it, you’ll be offered either a Recovery Key or iCloud recovery, to unlock it if you forget the password. When FileVault is enabled on a Data volume on the internal SSD of a Mac with a T2 or Apple silicon chip, the process is almost instant, as the Data volume is already encrypted, and your password is used to protect the key used to unlock the volume, as explained below. Thus no new encryption takes place.

That works differently for Intel Macs without a T2 chip, and for any Data volume on external storage, whose contents still have to be encrypted or decrypted, a process that can take many hours. In those cases, it’s best to enable FileVault when the Data volume has been freshly created, before filling it with more files, as encryption will then be quickest.

Enabling APFS encryption

The quickest and simplest way to encrypt an APFS volume is to do so when that volume is created, opting for APFS Encrypted format in Disk Utility. As the volume is empty to start with, encryption is instant, and everything added to that volume is encrypted as it goes along.

You can also opt for an existing APFS volume to be changed from unencrypted to encrypted. Select the volume in the Finder, open the contextual menu using Control-click, and there select the Encrypt command. Unless that volume is empty, macOS will then have to encrypt its current contents, which can take many hours if there are many files already in that volume.

How FileVault works

On Macs with T2 or Apple silicon chips, FileVault uses two features built into those chips: the Secure Enclave to protect and handle encryption keys, and a hardware encryption engine to perform encryption and decryption at blistering speed.

The Secure Enclave incorporates the storage controller for the internal SSD, so all data transferred between CPU and SSD passes through an encryption stage in the enclave. When FileVault is disabled, data on protected volumes is still encrypted using a volume encryption key (VEK), in turn protected by a hardware key and a xART key used to protect against replay attacks.

When FileVault is enabled, the same VEK is used, but it’s protected by a key encryption key (KEK), and the user password is required to unwrap that KEK, so protecting the VEK used to perform encryption/decryption. This means that the user can change their password without the volume having to be re-encrypted, and allows the use of special recovery keys in case the user password is lost or forgotten. Keys are only handled in the Secure Enclave.

How APFS encryption works

Encryption keys are protected at all times by encrypting and encapsulating them using a process known as wrapping. APFS uses the AES Key Wrap Specification in RFC 3394, using a secret such as a password to maintain confidentiality of every key.

APFS also uses separate volume and key encryption keys (VEK and KEK), so enabling the use of multiple KEKs for a single VEK, and the potential to change a KEK without having to decrypt and re-encrypt the whole volume, as used in FileVault. In APFS, VEKs and KEKs are stored in and accessed from Keybags associated with both containers and volumes.

The Container Keybag contains wrapped VEKs for each encrypted volume within that container, together with the location of each encrypted volume’s keybag. The Volume Keybag contains one or more wrapped KEKs for that volume, and an optional passphrase hint. These are shown in the diagram below.

Apple’s documentation refers to several secrets that can be used to wrap a KEK, including a user password, an individual recovery key, an institutional recovery key, and an unspecified mechanism implemented through iCloud. Currently, for normal software encryption in APFS, only two of those appear accessible: a user password is supported in both Disk Utility and diskutil‘s apfs verb, while diskutil also supports use of an institutional recovery key through its -recoverykeychain options. Individual and iCloud recovery keys only appear available when using FileVault, in this case implemented in software, either on Intel Macs without a T2 chip, or on all Macs when encrypting an external volume.

Because keybags are stored on the disk containing the encrypted volume, if the disk is connected to another Mac, when macOS tries to mount that volume, the user will be prompted to enter its password, and can then gain access to its contents. When FileVault is used to protect a Data volume on the internal SSD of a T2 or Apple silicon Mac, that volume can only be unlocked through the Secure Enclave of that Mac, and it isn’t possible to unlock it from another Mac (that’s also true when FileVault hasn’t been enabled on that volume).

Common example

The most common combination of encryption systems for a modern Mac (with a T2 or Apple silicon chip) is:

• FileVault encryption of the Data volume in the boot volume group forming the active system on the internal SSD, handled within the Secure Enclave, and managed using Privacy & Security settings.
• APFS Encrypted format of the Time Machine backup storage volume, handled using keys stored in the keybags on an external disk, and managed in the Finder.

In the centuries before photography came into widespread use, artists recorded landscapes and life in the countryside in paint. This series looks at the reality of life and work in the country using some of its finest paintings.

Introduction

From 1500, when about 80% of Europe lived in the country and worked in agriculture, to 1900, when 80% lived and worked in cities and towns. During the nineteenth century, it was supposed that those in the country were poor and disadvantaged compared to those in urban areas, but was that accurate, and how did it change?

1 Under the plough

Soil quality as the key to growing crops. Fertiliser came as dung from livestock, particularly sheep. The best way to prepare the soil to give the highest crop yields was by ploughing it repeatedly. This would also build the soil into ridges to drain water into furrows. Improvements in plough design.

2 The sower

Preparing the soil by removing stones. Sowing seed using broadcasting by hand, returning low yields compared to modern seed drills. Probably painted for longer than broadcasting remained in common use. Need for back-breaking weeding to allow crops to grow.

3 Cutting the corn

Different tools in use, including handheld sickle and hooks, and heavy scythes for mowing. Each used for different crops, and whether the straw was to be used as well. Cut grain formed into stooks to dry for removal.

4 Gleaning

Long-established and widespread ‘right’ of access to collect and remove the remains after the harvest had been cut. Although seen as the work of the poor, it was common among all, particularly women, as free food that would otherwise be wasted. It could also provide large amounts of grain in return for a few days work.

5 Threshing and processing grain

How harvested cereal is separated into grain, stems of straw, husk and other chaff. Increasing use of animals, first to thresh the grain from the cereal, then to power mechanical threshing machines. Some grain stored on the stem in grainstacks, as painted by Monet and others.

6 The mill

The use of wind and water power to grind grain into flour, in windmills and watermills.

7 Meat, milk, fleece and dung

Folding of sheep overnight so their dung would fertilise land growing crops, in the sheep-corn pattern of farming. Sheep as a replacement for humans in land clearances, especially in Scottish Highlands.

8 Cash and other crops

Crops grown mainly for sale, including buckwheat, sainfoin, flax for linseed oil and linen, madder for dyes and pigments, and clover to increase soil fertility.

9 Courses and crop rotation

Annual cycles of crops and land left fallow to preserve fertility of the soil. Two-year rotation in southern Europe, three and four in the north. Reflected in the patterns of fields seen in paintings.

10 Cattle

Cattle raised for drawing carts and ploughs, milk, meat and hide, often in areas less suitable for arable production, and woodlands. Twice-daily milking by milkmaids out in the fields. Milk manufactured into cheese, butter, and more. Cattle only in sheds in harsher winters. Often driven long distances to market on drovers’ roads.

11 Hay

Dried grass for animal fodder, harvested early in the summer, and sometimes later too. Mown using heavy scythes, dried in stacks or cocks, then into larger haystacks and baled for transport. Sold to supply working horses in towns and cities.

12 Potatoes

Increasingly important as a staple crop in the eighteenth and nineteenth centuries, often in gardens and smallholdings. Diseased by blight, resulting in famines and millions of deaths when crop failed, in Ireland and Scotland.

13 Market

Originally for farmers to sell surplus to consumers without merchants or middlemen. In nineteenth century taken over by dealers and merchants for their profit. Specialist markets for grain, fruit and vegetables, in major cities.

14 Trades

Mostly self-help, but specialist trades including blacksmith, metal forges, tinker to repair pots and pans.

15 The Year

Ploughing after autumn harvest, Spring sowing, calving, haymaking, harvest. Arable farming labour-intensive year-round, cattle less so and accommodating crafts and sidelines.

16 Drains and engines

Drainage of land for improvement, mechanisation using steam then internal combustion engines, railways for transport of produce.

17 People

Many paintings and photos are carefully posed and can mislead.

18 Idyll

Many living in the countryside worked hard but enjoyed their rural life and surroundings.

Although your Mac’s boot volume group, including the Data volume that’s almost always used for your Home folder, has to be in APFS format, you can still use Macintosh Extended or HFS+ format for other drives and their contents. This article provides advice to help you choose between the two Mac native file systems.

No choice

Other than the boot volume group, including the Data volume, APFS is only likely to be required to store Time Machine backups in recent versions of macOS. Although I think it’s still possible to continue backing up to an existing HFS+ backup store, you should stick to APFS for all new Time Machine backups.

One possible let-out, used for network backups, is to host a sparse bundle on another file system, and for that to use APFS internally. That’s how NAS can host Time Machine backups on Linux file systems such as Ext4 or Btrfs. However, I wouldn’t recommend putting that sparse bundle on HFS+, where they have known problems.

All new local Time Machine backups for recent macOS should be to Case-sensitive APFS, either encrypted or unencrypted.

APFS special file types

There are two types of file that are special to APFS and don’t exist in HFS+. Although they also exist in some other modern file systems, they can’t generally be converted between those and APFS.

Sparse files

Most modern file systems store files that contain significant amounts of blank or absent data in a special sparse file format. In APFS, this is implemented by only allocating file extents to those blocks that do contain data. In many cases, this can save significant disk space. Initially, sparse files were unusual in APFS, but over time they have become increasingly common, and can now be found in some types of disk image, virtual machine storage (VMs), and in databases. Note that disk image types whose name includes the word sparse, sparse bundles and sparse disk images, don’t use sparse file format at all, but are the victims of an unfortunate name collision.

Neither macOS nor APFS can simply convert regular files to sparse format; for a file to be written in sparse format, the code writing it must explicitly skip the empty space. As a result, sparse files are prone to explode to full size when they’re copied or moved unless that’s between two local volumes both using APFS. Examples of where you should expect them to explode include:

• copy or move to HFS+, as that has no sparse file format
• copy between Macs using AirDrop or file sharing
• back up to network storage, although local Time Machine backups to APFS should preserve them
• copy or move to any other local file system other than APFS, even if that file system has its own support for sparse files.

In each of those cases, sparse files explode in size as they’re copied from the source volume. If you have a 100 GB sparse file that only takes 20 GB of local disk space, when it’s copied to a local HFS+ volume, the full 100 GB has to be transferred.

One potential workaround is to compress the sparse file before transferring it. All good compression algorithms will work efficiently on the blank space in the file, so when compressed its size could be as small as the original sparse file. However, when it’s decompressed, even on another APFS volume, it will explode to full size. For disk images, that can be corrected by mounting them, as APFS will then trim their contents, and the disk image should be saved back into sparse format.

Clone files

These are two distinct files that share common data, normally the result of duplicating the original within the same APFS volume. Those two cloned files then only require the storage of the whole file, plus those data blocks that differ between them. This only works within the same volume, and the moment that either of the clones is moved or copied to any other volume, it assumes full size, as it can no longer share data with the other clone. Clones can’t span two volumes.

However, most other file systems don’t support file cloning in this way. When you duplicate a file in an HFS+ volume, there’s no shared data between them, and the two require twice the amount of space as one.

Benefits

In terms of disk space used, the benefits of sparse and clone files aren’t as obvious as you might expect. Because of their potential to swell to full size, sparse files can’t be copied to a volume that isn’t large enough to cope with that, but once they have been copied they only require their current size on disk.

As far as you’re concerned, greatest benefits come in speed of handling, and effects on SSD ‘wear’. Creating clone files is almost instant, even if they’re huge, and because of their efficiency in the use of storage extents they minimise erase-write cycles on SSDs.

Snapshots

I have recently explained how snapshots work, and how you can use them alongside proper backups to restore lost or damaged files. Snapshots are used in most modern file systems, but don’t exist in HFS+. If you want local snapshots of any volume connected to your Mac, you’ll most likely have to use APFS unless you know how to use something more exotic. Note that, unless you’re Time Machine, you can’t copy snapshots to another volume or drive, but you can mount them and copy their contents to another volume.

Encryption

Unlike HFS+, APFS was designed with encryption built in. This significantly improves its performance with encrypted volumes, and makes them more secure. If you need to store files in an encrypted volume, you should prefer APFS for that volume.

Volumes share free space

In HFS+, volumes have fixed size, as they’re disk partitions. Although you may be able to change partitioning that’s already in use without losing data from any of the volumes involved, that’s never guaranteed.

In APFS, volumes share free space with others within the same container. While you can set limits on individual volume size, this makes management of free space much easier, allowing volumes to occupy the space they require, instead of that being predetermined.

Directory hard links

These aren’t available in APFS, but are supported in HFS+, where they’re used extensively in old-format Time Machine backups. They work like regular hard links, but act on directories rather than individual files. They can’t be copied in any way to an APFS volume, but can be used to reconstitute a volume. This ensures a new Mac that only uses APFS can still access old Time Machine backups from a previous Mac: macOS retains full support for HFS+ and its directory hard links, so you can mount those old backups and access them through the Finder.

Hard disk fragmentation

APFS was designed for use on SSDs and the Flash drives used in Apple’s devices. It has design features that will never work well on hard disks, as they fragment not only file data, but the file system itself. While it’s possible to boot an Apple silicon Mac from a hard drive, you wouldn’t want to run your Mac from one. With an active file system such as that on your Mac’s Data volume, files and the file system get steadily more fragmented until the drive eventually grinds to a halt.

Hard disks using APFS normally remain usable for a year or more when they store files that don’t get changed very often, like media libraries, and in many cases backups, including Time Machine’s. Experience with the latter suggests that most cope well, but in extended use they too eventually become too fragmented to continue. There currently isn’t any effective solution to that fragmentation, other than wiping the volume and starting from scratch. Because Time Machine’s backups are stored as snapshots, they can’t even be copied to another drive to help.

Reliability and maintenance

APFS has been designed to be far more robust and reliable than HFS+. A longstanding problem with HFS+ before journalling was introduced was its propensity to accumulate minor errors that eventually lead to catastrophic failure. One common reason for this was sudden restarting or other interruptions to file system operations. Journalling was added to reduce the chances of those leading to file system damage or inconsistency, and for that reason, you should never use HFS+ without journalling.

One key feature in APFS that makes errors highly improbable is its use of copy-on-write for all file system metadata. This ensures that changes made to the file system are almost guaranteed to remain consistent, even when suddenly interrupted. Unfortunately, one of the side-effects of copy-on-write is fragmentation of file system metadata, thus its main limitation on hard drives.

Conclusion

If your Mac is running a more recent version of macOS, from Mojave onwards, all its SSDs should by default use APFS. Deciding which to use for hard disks is more difficult, and you need to weigh up their advantages and disadvantages carefully. Unless the volumes on that disk are going to see frequent changes, when fragmentation could result in poor performance, in most cases APFS should now be the default.

References

HFS+
Inside the file system: 1 Disks and partitions
Inside the file system: 2 HFS+ volumes
Inside the file system: 4 Summary and references

APFS
APFS: Files and clones
APFS: Directories and names
APFS: Containers and volumes
APFS: Snapshots
APFS: Encryption and sealing
APFS: Special file types
APFS: Command tools
APFS: Beyond, to vfs and volfs
APFS: Log entries
APFS: Extended attributes revisited
APFS: How sparse files work

Today I commemorate the centenary of the death of one of the New York School of Art’s most famous and most accomplished alumni, George Wesley Bellows. In the first article outlining his career and art, I had reached the First World War when he was a pioneer of the Ashcan School. This article concludes the account.

During the war years, Bellows continued to paint scenes of working life. His Builders of Ships / The Rope is unusual, in depicting a brief revival in the building of wooden ships at a yard in Camden, Maine, during Bellows’ summer season painting there in 1916. A recurrent theme for paintings, wooden ship construction was even then a traditional craft, as celebrated here by Bellows.

For his Sand Cart from 1917, Bellows travelled to the coast of California, where he again caught working men engaged in manual labour, this time against a different coastal background. This painting was shown on his return to New York, where it was well-received by critics, who compared it with the coastal paintings of Winslow Homer.

Bellows was strongly opposed to the entry of the US into the First World War, and was horrified by the many stories of atrocities allegedly committed by German troops when they had entered Belgium. One, where the Germans had apparently used the local population as a ‘human shield’, he expressed in The Barricade (1918).

He had also been developing his skills of lithography, and in 1916 installed a press in his studio. From then on he produced increasing numbers of lithographs, many of which developed anti-war themes.

In the summers of 1918 and 1919, Bellows was in Middletown, Rhode Island, with his family. During the second of those he painted Three Children, which was installed in the Green Room of the The White House in 2007. The three children shown are believed to be Bellows’ two daughters and the son of a local farmer, although the painting is as much about the rich rolling countryside beyond them.

After the war, Bellows turned to more figurative and portrait painting, including this Nude with Fan (1920). This wasn’t his first nude: he painted that in 1906, and it has now become the second painting by Bellows to enter a British collection. This is remarkable though for its richly lit landscape vignette, a tradition going back to the northern Renaissance.

Tennis at Newport (1920) is one a series of paintings by Bellows in 1919-20 from sketches and studies made during summer tennis tournaments at the Newport Casino in Rhode Island. His interest is less in the sport taking place, and more in the social event surrounding it. This painting is set in the late afternoon, as the shadows grew long.

In 1920, he and his family started spending the whole summer in Woodstock, New York (State), and by 1922 they had a house and studio built there. Situated in the Catskill Mountains, this area had long been a favourite with US landscape painters.

Of all his paintings, I find his late landscapes the most moving and intriguing. He painted The White Horse (1922) on a farm near Woodstock. Seen in the fall colours of November, its effect is heightened by the light cast through broken shower clouds, making the white horse look almost supernatural.

In the 1920s, Bellows painted his family more, including this carefully-posed portrait of his wife, Emma Story. Emma in a Purple Dress (1920-23) proved one of his most challenging works, and he scraped sections such as the head repeatedly before he was content with them.

Bellows is perhaps best-known for his paintings and prints of boxing matches, many of them clandestine. Dempsey and Firpo (1924) shows a famous historic boxing match between the heavyweights Jack Dempsey, who had been world champion since 1919, and Luis Ángel Firpo, an Argentinian challenger. This took place in the Polo Grounds of New York City on 14 September 1923.

From the start of the first round, the fight was gripping in excitement, with Dempsey knocking Firpo down seven times. Towards the end of the first round, Dempsey was trapped against the ropes, and Firpo knocked him out of the ring, the moment that Bellows shows here. Dempsey finally knocked Firpo out late in the second round. This was made from contemporary press photographs.

Painted just a year before Bellows’ sudden death, his Summer Fantasy (1924) contrasts with almost all his preceding paintings. Using a formal and classical composition, he has brought together images of archetypes in a lush green park, with the Hudson River behind. Ladies in fine, flowing white dresses promenade with their husbands. Horses and their riders, some in the elegance of side-saddle, cross in the middle distance. The sails of boats on the river are backlit by the setting sun.

This has been interpreted as an allegory of life, going from the baby in the pram in the right foreground, through marriage, to the final years. But we will never know where it was going to lead Bellows’ brush in the future, because in the New Year of 1925, he suffered appendicitis, which he left untreated. This resulted in peritonitis, from which he died on 8 January, in New York City. He was only forty-two.

References

Wikipedia
H V Allison’s online catalogue raisonné

Brock C ed. (2012) George Bellows, Prestel. ISBN 978 3 7913 5187 2.

Recent information from Apple about Power Modes available on Apple silicon Macs doesn’t match that found, and lacks detail. For example, according to that article all Mac mini M4 2024 models feature both Low and High Power modes, while a MacBook Pro 16-inch Nov 2023 M3 Pro has neither. In reality, only Mac mini models with the M4 Pro support High Power mode, and that MacBook Pro M3 Pro, like many other Apple silicon models, does support Low Power mode, but not High.

A first look at GPU performance and power use demonstrated that Low Power mode on an M4 Pro resulted in a dramatic reduction in power to a third of that expected, with a disproportionately small reduction in render performance to only 69%. However, Low Power mode in the M3 Pro resulted in no detectable change in GPU performance or power use. This article extends the comparison to CPU cores in both chips.

CPU core frequency

Most of the action here concerns Performance (P) cores, although E cores get the occasional look-in. Frequency of P cores is labile, and they don’t have a single operating frequency that’s increased by a ‘boost’ feature or reduced by ‘throttling’. Each cluster of P cores, six in the M3 Pro and five in the M4 Pro, runs at the same frequency as determined by macOS, according to its rules.

For example, cluster frequency may be reduced as the number of threads running in that cluster increases, and, as I’ll show below, can be set at frequencies well below maximum for other reasons. From the first base M1 chip, gaining an understanding of core frequency control has been central to understanding how these chips function.

Methods

The results described below were obtained using similar methods to those detailed in previous work on M1, M3 and M4 chips (links at the end). Tests used to assess core performance were a tight floating point loop in assembly language, and a similarly tight loop of NEON assembly code for vector processing. These use registers alone, without accessing memory in the loop, so are intended to be core-intensive and not representative of real-world code.

Floating point and NEON tests were run in 1-14 threads on the M4 Pro with Power Mode set to Automatic, and to Low Power. Time to complete each set of threads was recorded using Mach timing, and each test run was analysed in 0.1 second collection periods using powermetrics cpu_power sampler.

Performance

This graph shows time taken to complete each set of test threads against the number of threads being run. Black lines show results for the floating point test, which follows that expected. Up to a thread count of 10, when all P cores in the M4 Pro are fully occupied, time remains fairly constant, then increases as threads spill over to be run on the slower E cores, until they are also full.

NEON performance times, shown in red, appear most peculiar. They are fairly constant up to 5 threads, then grow increasingly longer until they spill over to the E cores above 10 threads, when their rate of increase is reduced, despite being run on slower and less performant E cores.

Frequency and power

Looking at individual test data from powermetrics revealed a striking difference between floating point and NEON tests, illustrated above for their tests with 10 threads, thus fully occupying both clusters of P cores. Here, floating point power measurements are shown in red, and those for NEON in black.

Power during floating point tests changed as expected from previous tests. It rose steeply to a peak as the threads were loaded, then settled to a steady value until threads were completed, then dropped rapidly back to near-idle. What differs here from the Automatic power setting is that, regardless of the number of threads, P cores were run at a frequency of 3,624 MHz, significantly below normal, reducing average power use to about 1,100 mW per thread.

When NEON threads were run in Low Power mode, the initial peak was much higher, and close to that measured with the Automatic power setting. It then fell over the following 0.3 seconds to a level that appeared independent of the number of threads between 5 and 10, at an average of about 14,000 mW as the total for all P cores. Between 1-5 threads, cluster frequency appeared fixed at 3,624 MHz, the same as that for floating point. As the number of threads rose beyond 5, frequencies fell progressively to 2,616 MHz, indicating they were being reduced by macOS, most probably to limit temperature rise.

Power differences

The following two graphs show average power use when running floating point threads, by the number of threads being run, first for the Automatic power setting, then for Low Power. Points are shown with error bars representing +1 standard deviation about the mean.

When running in Automatic power mode, each additional floating point thread required 1,300 mW on P cores, and 110 mW on E cores. In Low Power mode, threads on P cores were reduced to 1,100 mW, with no significant change on E cores.

NEON threads were more complex.

In Automatic power mode, each additional NEON thread required 3,000 mW on P cores, and 280 mW on E cores. In Low Power mode, for 1-5 threads, each required 2,500 mW. There was then a transition at 6 threads, and from 7 threads upwards power use was constrained to about 14,000 mW, rather than climbing to the peak of over 32,000 mW measured in Automatic mode.

M3 Pro

At this point, I performed a limited number of NEON tests on my M3 Pro, to see if its CPU cores behaved similarly when set to Always for Low Power mode. They didn’t, and instead ran all NEON threads at a cluster frequency reduced to 2,808 MHz, compared with 3,576-3,624 MHz when run with Low Power mode set to Never. That extended the time to execute threads from 2.1-2.7 seconds to a steady 3.0 seconds regardless of their number.

Energy use

While power use is important in determining cooling requirements, for those using Low Power mode when their Mac is running on battery, energy use is often more important. Reducing cluster frequency not only reduces power use but also extends the time to complete the same computational task. If frequency reduction reduces power used to 50% but tasks take twice the time, then the only net saving in energy would be that required by cooling fans.

Although I may return for more extensive calculations of total energy required for the M4 Pro, figures for the M3 Pro appear impressive:

• for a single NEON thread, total energy used fell from 6.7 to 3.6 KJ
• for 6 threads, its full P cluster, total energy fell from 32 to 20 KJ
• for 10 threads, 6 on P cores, and 4 on E, total energy fell from 41 to 26 KJ.

Those are for the CPU cores alone, and don’t include savings from memory, SSD, or cooling fan use.

What does Low Power mode do?

The effects of Low Power mode differ according to Apple silicon chip. For the M4 Pro they include:

• reduction in P core frequency, but no change in E core frequency for high QoS threads that have spilt over from P cores;
• further reduction in P core frequency to limit total power to about 14 W, so restricting heat generation and allowing reduced fan use;
• reduction in GPU core frequency to reduce power use to about one third at maximal tasks;
• significant reduction in CPU and (probably) GPU energy use.

For the M3 Pro they include:

• reduction in P core frequency, but no change in E core frequency for high QoS threads that have spilt over from P cores;
• no further reduction in P core frequency was necessary, as power remained below 10 W even with 10 NEON threads running;
• no alteration in GPU core frequency or power use;
• significant reduction in CPU energy use.

As to which Apple silicon models support which set of features, I’ll leave it to Apple to get its facts straight in an updated version of its support note.

References

Inside M4 chips: CPU power, energy and mystery
Inside M4 chips: Matrix processing and Power Modes
Power Modes and Apple Silicon GPUs
Evaluating M3 Pro CPU cores: 1 General performance

Tomorrow I commemorate the centenary of the death of one of the New York School of Art’s most famous and most accomplished alumni, George Wesley Bellows. In this first article outlining his career and art, I cover his early years before the First World War when he was a pioneer of the Ashcan School, and conclude tomorrow with his later years.

Born in 1882 and brought up in Columbus, Ohio, Bellows’ first choice of career was as a sportsman. He studied at the Ohio State University between 1901-04, where he played for its baseball and basketball teams, and worked as a commercial illustrator. His sporting background is unusual for a painter, and was to influence his art later.

Gardiner’s Bay from Sag Harbor (1899) is an early watercolour from his High School days, and shows this undeveloped little bay at the far eastern end of Long Island, where Bellows’ family returned for their summer vacations.

Bellows then decided to become a painter, left university just before he was due to graduate in 1904, and moved to New York, where he studied at the New York School of Art, mainly under Robert Henri.

When he was a student in New York in 1905, he painted Bethesda Fountain (Fountain in Central Park). It shows, in sombre earth colours, this central feature of Bethesda Terrace in New York’s Central Park, a local motif. This bronze statue was designed by Emma Stebbins, and in those days was still relatively new, having been unveiled in 1873. More properly known as The Angel of the Waters Fountain, it refers not to Bethesda, Maryland, but the biblical location.

By 1906, Bellows had set up a studio in Broadway Street with another student, and was busy recording life in New York City.

Forty-two Kids (1907) was one of the earliest recognisable works of what became known as the Ashcan School, and depicting the reality of city life in works “full of vitality and the actual life of the time”, in Robert Henri’s words. Here an incoherent gathering of street urchins and other kids has taken over a tumbledown wharf in East River for swimming, sunbathing, smoking, and generally hanging about. Although now used generally of children, at the time the word kids had a more specific meaning, referring to the unruly children of working class immigrants living in the tenements of Lower East Side. Bellows exhibited this painting the following year, and it was his first to be sold into a private collection.

Bellows’ views of New York are in stark contrast to the skyscrapers of Colin Campbell Cooper, although they were painting the city at the same time. Bellows’ Pennsylvania Station Excavation (c 1907-1908) shows the deep excavations made for the new station during the winter, caught in the last light of the day.

Excavation at Night (1908) is a nocturne, perhaps of the same site, again in the winter, with a patch of snow still on the ground.

In 1908, Bellows joined fellow students in organising an exhibition focussed on urban art. Some critics voiced concerns at the apparently crude style of his paintings, but others felt them to be suitably daring. He also started to spend his summers in Maine, following the examples set by William Merritt Chase and Robert Henri.

Bellows’ Haystacks and Barn was probably painted out in the Maine countryside during the summer of 1909.

Returning to the East River in New York, his The Bridge, Blackwell’s Island (1909) shows the Queensboro Bridge linking Manhattan with Queens. Its piers rest on Blackwell’s Island, now known as Roosevelt Island. This view was painted from the Manhattan end in December 1909, shortly after it had been opened. At the time it was the greatest cantilever bridge in the world.

From 1911, he associated with radical artists in the ‘lyrical Left’, and concentrated again on depicting the lot of working people.

New York (1911) balances the world of the people of New York with that of their buildings. It was shown that year in the annual exhibition of the National Academy of Design, in New York, and annually thereafter for the rest of Bellows’ career, but wasn’t sold until after his death.

Men of the Docks (1912) has the unique distinction of being the first major work of a US artist to be purchased by The National Gallery in London, which paid over $25 million for it in 2014. These labourers have arrived seeking work in the docks, in the depths of winter. The figures are seen against a backdrop of a cargo ship and grey skyscrapers behind.

Bellows’ famous Cliff Dwellers (1913) shows the largely immigrant population of tenements in Lower East Side, whose children featured in Forty-two Kids. In 1916 this was the first painting to be purchased by the county of Los Angeles for its new museum of art, where it remains today.

Rock Reef, Maine (1913) was painted when Bellows was out on the Maine coast.

References

Wikipedia
H V Allison’s online catalogue raisonné

Brock C ed. (2012) George Bellows, Prestel. ISBN 978 3 7913 5187 2.

Snapshots are a popular feature of modern file systems like APFS. This article explains what they are, how they come about, and what their benefits and problems are in macOS.

What is a snapshot?

Each volume, whether in HFS+ or APFS, is a complete file system, containing all the information about the files within it, details of directories or folders, and where all the data for those files is to be found on the disk hosting that volume. File system data is constantly changing, as files are created, updated and deleted. When a file is deleted, its entry in the list of files in that volume is removed, and the storage blocks used to contain the file’s data are marked for removal, thus to be returned for reuse.

If you were to make a complete copy of that file system, that would describe the volume at that instant in time. To accompany that you could then preserve all the storage blocks containing its file data. From that moment on, instead of returning storage blocks for reuse, if you retain them, you could revert that volume to the state it was in at that instant. That’s just what a snapshot does.

Concentrating for a moment on a single file, the file system has an inode record containing attributes for that file, such as its time of creation, and those are linked to a list of the storage blocks containing the file’s data, its file extents. At the moment that a snapshot is made of that volume, those inode records and extents are copied to form the snapshot itself, and all the data blocks listed in the extents must be preserved.

This shows the same file in a snapshot and in the current volume, a little after that snapshot had been made. Extents for the data of the earlier version of that file contained in the snapshot are shown at the top, and consist of blocks EA, EB, EC and ED. After that snapshot was made, the file was edited and now consists of the blocks shown at the bottom, EA, FB, FC and ED.

Thus, the extents listed for that file in the snapshot consist of two blocks, EA and ED, that are currently in use and included in its current extents, and two blocks, EB and EC, that were deleted after the snapshot was made. As those are referenced in the snapshot’s extents, those storage blocks are retained to enable the snapshot to restore the volume’s previous state. When that snapshot is deleted, blocks EB and EC will then be returned to the pool of free blocks for erasure and reuse.

Snapshot size

Snapshots are stored within the same container holding the volume, and are linked to the current volume, although not stored inside it (as that would create a recursive volume structure and catastrophe). The size of the snapshot itself, the copy of the file system, is relatively small, but the size of the retained storage, blocks EB and EC in the diagram, can be far larger.

Imagine that, just after making a snapshot, you delete a 100 GB file, like a Virtual Machine. So long as that snapshot remains, the storage occupied by that huge file has to be retained, and can’t be released for reuse. So that snapshot has a minimum effective size of 100 GB until it’s deleted.

If you make a snapshot now and keep it for several days, it grows steadily in size. Each storage block containing deleted file data must be retained as long as the snapshot is kept, so over hours and days, that snapshot accumulates more retained data, and grows. Ultimately, it could come to occupy all the space in that container, unless you delete the snapshot. When you do, all its retained storage is released for reuse, and free space grows as a result.

Because the largest snapshot is normally the oldest, as it contains the most preserved file data, when deleting snapshots it’s usual to delete the oldest first. If you did want to delete a newer snapshot, APFS would work out what file data can be removed without affecting older snapshots, just don’t expect the removal to free up as much space.

Using snapshots

Because HFS+ was designed in the last century for use primarily on rotating hard disks, it doesn’t support snapshots at all. They’re a central feature of APFS, so we have more limited experience of working and living with their peculiarities.

Making a snapshot is so quick as to be almost instant, and typically takes around 0.01 second, but deleting one takes upwards of 0.2 seconds because all it retained data have to be marked for reuse, and any remaining snapshots left intact.

Snapshots can be used like a backup that has been made to the same disk. As they’re a complete file system, they can be mounted like any other volume, and you can use that to copy files, or even to restore the current volume, a process often known as rolling back to that snapshot. Although those are convenient, as they don’t require a separate backup, they depend on much of the contents of the current volume, and can easily be affected by the same corruption or other problems affecting the volume you’re trying to fix. So they’re an additional benefit and not a substitute for proper backups made on separate and independent storage.

Time Machine and third-party backup utilities therefore make and maintain snapshots as well as regular backups. Time Machine does so because it uses the data in snapshots to help create its backups. So every hour, when Time Machine comes to make an automatic backup, it creates a local snapshot of each volume it’s going to back up. To prevent those snapshots from taking ever-increasing amounts of storage space, it automatically deletes those snapshots after 24 hours. Time Machine’s backups are also snapshots, but are specially created on backup storage, not alongside the volume being backed up like its local snapshots.

Scope and limits

There are two other important properties of snapshots in APFS: they’re always whole-volume, and are read-only.

Some modern file systems allow you to create snapshots of only part of a volume, but APFS doesn’t. All its snapshots contain the whole contents of a volume. If you add a folder from that volume to the list of exceptions for TM backups, its local snapshots will still contain that folder, and can’t be excluded from the snapshot.

This is good in some ways, as it means that you can always copy or restore from a snapshot even when some of its contents were excluded from your backups. It’s bad in others if you put very large files into a folder in a volume that’s being backed up: changes in those large files will make that volume’s snapshots very large. If you want to exclude files from taking up space in snapshots, then you have to move them to a separate volume that isn’t backed up at all, so doesn’t have snapshots made of it.

If a snapshot does contain a very large or unwanted file, because snapshots are read-only, there’s no way to delete that file from the snapshot, and it’ll remain there until the snapshot itself is deleted. Other modern file systems may allow you to tamper with a snapshot after it has been made, but APFS doesn’t, so you can always rely on that snapshot remaining faithful to the original volume.

One final limitation at present is that you can’t copy a snapshot, in particular to another storage drive. You can mount that snapshot and copy its contents to another volume, make a snapshot of that volume, and use that, but that’s not the same.

Maintenance

You can maintain and remove snapshots using a range of different utilities, including Disk Utility (where you need to enable their display in the View menu), third-party backup utilities such as Carbon Copy Cloner, and some other tools like BackupLoupe.

Some features in macOS still don’t handle snapshots at all well. For instance, Storage in General settings usually classifies the space occupied by snapshots as ‘system data’, which is vague and unhelpful. Unless you have a third-party utility, it’s best to trust the management of snapshots to Disk Utility, which handles them most reliably.

Summary

• A snapshot is composed of a copy of the file system at an instant in time, together with all preserved file data required to recreate that volume as it was at that instant. It’s stored alongside that volume, in the same container.
• The size of a snapshot is almost entirely determined by the amount of file data preserved by it. As more changes are made to the current volume, so more file data must be kept to be able to recreate the volume as it was when the snapshot was made, and the size of the snapshot grows.
• Snapshots can mounted as a volume, and files copied from them, or the whole volume restored. They’re not independent from the current volume, though, so can’t replace proper backups on separate storage.
• Time Machine makes hourly local snapshots of each volume it’s backing up, and automatically deletes them after 24 hours. Snapshots are also used by other backup utilities.
• Snapshots include everything in a volume, without exception. To ensure files aren’t included in snapshots, move them to a volume that isn’t backed up by Time Machine.
• You can’t remove anything from a snapshot once it has been made, as they’re read-only and immutable.
• You can’t copy snapshots.
• Space occupied by snapshots can grow large. Use Disk Utility or a third-party utility to inspect and maintain them.

References

APFS: Snapshots
Explainer: The arithmetic of snapshot size

Following her story of the transformation of Hippomenes and Atalanta, Venus resumes the account of her affair with Adonis, whom she had warned of the dangers of lions and savage beasts.

John William Waterhouse’s The Awakening of Adonis was completed in 1899 but wasn’t shown to the public until the following year, when it was hung at the Royal Academy’s summer exhibition. One of a series of his works telling stories of classical myths, it received great critical praise. Although Waterhouse shows an early moment in Adonis’s affair with Venus, where she’s the active partner, he hints at the outcome with a small group of red anemone flowers by his side. Those contrast with the white anemones on much of the rest of the grass.

Annibale Carracci’s Venus and Adonis from about 1595, three centuries before Waterhouse’s painting, is a superb painting of Venus, her winged son Cupid, and Adonis. The latter has his bow in his left hand, and his hounds by his side, as if about to go hunting. Carracci shows Cupid with an arrow in his left hand, and there’s a small red wound between Venus’s breasts, implying this is the moment that she fell in love with Adonis.

Paolo Veronese shows a later moment in the relationship between Venus and Adonis (c 1580), with Adonis asleep on his lover’s lap, and Cupid fondling the hounds. You can hear Cupid’s mother whispering forcefully to her son, telling him to restrain the dog from rushing forward, licking the face of Adonis, and waking him up. Veronese, as with most later artists, dresses Adonis in red, symbolising the blood that will be shed when he dies.

Titian takes us further into Ovid’s story, in his earlier painting Venus and Adonis, from about 1555-60. With the young Cupid asleep, cradled in a tree, Adonis wants to go hunting. He has his spear in his right hand, and his hounds on leashes held in his left. But Venus is terrified of what will happen, restraining him and telling the story of Hippomenes and Atalanta.

Peter Paul Rubens skilfully reversed Titian’s composition in his Venus and Adonis from the early seventeenth century. Adonis is now trying to depart to the left with his back to the viewer, bringing the beauty of Venus into full view, and strengthening its triangular composition. It also provides a natural place for Cupid, holding onto Adonis’s leg to stop him from going to his death. Cupid’s quiver, left on the ground behind him, is a reminder of the origin of the relationship.

Once Venus had left in her chariot drawn by swans, Adonis flouted her warning, and took his hounds out to hunt wild boar. They quickly found the scent of one, at which Adonis threw his spear. The spear struck the boar a glancing blow, and it was able to shake the weapon loose. As the young man was running away in fear, the injured boar charged at him, and gored him deeply in his groin.

Adonis lay dying from his wounds on a patch of yellow sand as Venus passed by in her chariot, on her way to Cyprus. She heard his groans of agony, stopped, and found him almost dead in pools of his own blood. She tore her clothes in grief, beat her breast, and cursed the Fates. She resolved to make a permanent memorial to him in the form of the blood-red anemone flower, and his blood was transformed into those flowers.

The manner of Adonis’s fatal wounding is seen as poetic justice: those who live by the sword, die by the sword, and the retribution for his adulterous relationship with the goddess Venus, Vulcan’s wife, is to be gored in the groin. This was clearly no scene for the visual explicitness of a painting.

Hendrik Goltzius painted this breathtakingly foreshortened projection of the Dying Adonis (1609) on a square canvas stood on one corner, to frame the figure tightly. A token splash of blood on his thigh is matched by crimson anemone flowers, although Venus hasn’t yet arrived on the scene, and is at the apex, still in her chariot. Beside Adonis is his spear, although there’s no sign of blood on its tip.

In or just before 1614, Rubens made this oil sketch of Venus Mourning Adonis, a more complex composition with the addition of three Graces, and the young Cupid at the right.

Rubens’ finished Death of Adonis was completed in 1614, and retains the same composition. A rather portly Venus cradles her lover’s head as the Graces weep in grief with her. Rubens has been more generous with the young man’s blood, which is splashed around his crotch and spills out onto the ground, where the hounds are sniffing it. The fateful spear rests under Adonis’s legs.

I particularly like Cornelis Holsteyn’s Venus and Cupid Lamenting the Dead Adonis from 1647. Although he’s coy about showing much blood, his arrangement of Adonis’s body is novel, and his use of colour apt. Venus sheds real tears as she’s about to sweep her lover into her arms, and in the distance is the shadow of a wild boar with the hounds in chase.

Marcantonio Franceschini is one of the few artists to show The Metamorphosis of the Dead Adonis, in this painting from about 1700. Venus is sprinkling a jar of nectar over the corpse of her lover, and anemones are already bursting into bloom.

With that, Ovid closes book ten of his Metamorphoses.

I hope that you enjoyed Saturday’s Mac Riddles, episode 289. Here are my solutions to them.

1: The most affordable Mac ever at under $500 has just shrunk further.

Click for a solution

Mac mini, 2005

The most affordable Mac ever (Apple’s tagline for it) at under $500 (its starting price was $499) has just shrunk further (the original Mac mini, released on 11 January 2005, in its latest M4 incarnation is even smaller).

2: Apple’s most personal device yet came in April with San Francisco Compact.

Click for a solution

Apple Watch, 2015

Apple’s most personal device yet (Apple’s tagline for it) came in April (although announced the previous September, it was released on 24 April 2015) with San Francisco Compact (the face in Apple’s new system font designed for use on it).

3: With four fonts and a canon inside, it co-founded a desktop revolution.

Click for a solution

LaserWriter, 1985

With four fonts (it came with just Times, Helvetica, Courier and Symbol with PostScript) and a canon inside (the print engine was made by Canon), it co-founded a desktop revolution (with the Mac and Aldus PageMaker, it founded the Desktop Publishing revolution when it was released on 1 March 1985).

The common factor

Click for a solution

They are major Apple products first released 10, 20 and 40 years ago.

I look forward to your putting alternative cases.

Some recent Apple silicon Macs offer High and Low Power modes that appear to differ from the Low Power mode offered previously. This article discovers what they do, in particular how these modes affect the GPU.

New Power modes

According to Apple’s most recent explanation of Power modes in Apple silicon Macs, these are restricted to specific models. Low Power mode is apparently only available in:

• MacBook Pro with M1 Max, M2 Max, M3 Max or M4 chips,
• iMac with M3 or M4 chips,
• Mac mini with M2 or M4 chips.

Low Power mode “reduces energy use to increase battery life” and, in macOS Sequoia 15.1 and later reduces fan speeds to minimise generated noise and to reduce power use.

High Power mode is only available in:

• MacBook Pro with M1 Max, M2 Max, M3 Max or M4 chips,
• Mac mini with M4 chips.

High Power mode primarily runs the cooling fans at higher speeds to allow longer sustained high performance, and “can improve performance in graphics-intensive workflows”. Apple gives examples of the latter, including colour grading 8K video, video editing and 3D apps.

If your MacBook Pro doesn’t have an earlier Max variant or an M4, then what it refers to as Low Power mode in its Battery settings doesn’t appear to be Low Power mode according to that article. That might be the Low Power mode apparently introduced for MacBook and MacBook Pro models from early 2016 and later, when running macOS Monterey 12.0 and later. Juli Clover of MacRumors stated that “reduces the system clock speed and the display brightness in order to extend your battery life even further.”

Apple uses the words energy and power interchangeably, and in places refers not to Power Modes, but to Energy Modes, which is surprisingly inconsistent and thoroughly confusing.

Previous results

When recently investigating CPU core power use in the M4 Pro, I examined the effect of Low and High Power modes. As might be expected from Apple’s description, High Power mode had no effect on CPU core frequencies, their control, power use or performance.

However, Low Power mode had substantial effects on core frequency, performance and power use. When running floating point tests in 10 threads, their cluster frequency was reduced from 3,852 to 3,624 MHz, 94% of Automatic and High Power. That reduced power use from a mean of 13.9 W to 11.2 W, and increased the time to complete threads. Time taken by floating point threads increased to 106% of Automatic and High, while that for NEON increased to 135% and vDSP_mmul to 177%.

My previous measurements in M4 Pro CPU cores found peak average CPU power use of 14 W when running floating point instructions, 33 W for NEON, and 36 W for vDSP_mmul.

Assessing the GPU

My previous attempts to find a performance test that will reliably put maximum load on Apple silicon GPUs had limited success, but Blender Benchmark now appears capable, and has been used extensively. This runs three demanding renders using Metal, and reports for each the estimated number of rendered path tracing samples per minute. Running the Blender 4.3.0 version on the GPU using Metal results in consistent 100% active residency and maximum frequency for periods of several seconds. The standard test sequence used here renders three scenes, named monster, junkshop and classroom.

Tests were performed on a Mac mini M4 Pro with 20 GPU cores running macOS 15.2, thus one of the systems able to make use of both High and Low Power modes, and a MacBook Pro M3 Pro with 18 GPU cores running macOS 15.2, one of the models previously claimed to use ‘old’ Low Power mode, but excluded from the list of those capable of either High or Low Power modes.

GPUs were assessed using the powermetrics command tool’s gpu_power sampler for sample periods of 0.1 second over a total of 5 seconds early in each of the test renders. Activity Monitor’s GPU History window was used to check when each of the test renders had reached 100% GPU, at which point the powermetrics samples were collected into a file. Once the three renders had completed, their scores were recorded and the Blender Benchmark app was quitted. Tests were performed for:

• M4 Pro, for Automatic, High Power and Low Power,
• M3 Pro, for Low Power Mode Never and Always.

To ensure the latter had fully engaged, the MacBook Pro was also set to Always and restarted on battery power alone, but that made no difference to render performance.

Power

Differences between GPU performance were most apparent when comparing Automatic and Low Power modes on the M4 Pro, as shown in the chart below.

GPU power measurements given by the gpu_power sampler are shown against time over the 5 second period during the first, monster render. Filled circles and the regression line in black are those with the Automatic setting, and those in red are at Low Power. Thus, the obvious effect of Low Power mode is to reduce GPU power from about 20 to 6 W.

This chart adds measurements made during High Power mode in purple. If anything, power use was slightly lower in High Power than in Automatic mode, but there’s extensive overlap between values.

This adds measurements made with Low Power set to Never on the M3 Pro, shown in blue. Those too overlap with the M4 Pro set to Automatic and High Power, and are about 18 W. No difference was seen with the M3 Pro Low Power mode set to Always.

Blender Benchmark results are compared in the table below.

As expected, performance was almost identical between M4 Pro automatic and High Power modes, and between M3 Pro normal and Low Power modes. The only substantial differences were between M4 Pro automatic and Low Power, and between M4 Pro automatic and M3 Pro Low Power Never modes.

In the M4 Pro, engaging Low Power mode reduced GPU render performance to 65-71% of normal. The 18-core GPU in the M3 Pro achieved 66-72% of the performance of the 20-core GPU in the M4 Pro. Given that the M3 Pro has 90% of the number of cores, that implies that the GPU cores in the M4 Pro are significantly more performant than those in the M3 Pro, as has been claimed.

This table brings together performance and power use for the monster render alone. On the M4 Pro, Low Power mode delivered 69% of the render performance using about a third (32%) of the power. That contrasts with the M3 Pro, whose 90% core count used 90% of the power to deliver 72% of the performance, relative to the M4 Pro.

Settings

In the MacBook Pro M3 Pro, Battery settings explicitly refer to Low Power Mode. As this is completely different from the ‘new’ Low Power mode, that’s misleading.

In the Mac mini M4 Pro, Energy settings explicitly refer to Energy Mode, offering Low Power (at the top of the popup menu) and High Power (at the bottom of the popup menu).

Terms used and Apple’s detailed guidance need to be rationalised and made consistent across all recent Macs.

What Low Power mode does

Detailed comparison between powermetrics measurements in automatic and Low Power modes on the M4 Pro confirm that there are substantial changes to control of GPU cores. Running any of the three renders normally results in GPU cores being run at their maximum frequency of 1,578 MHz with 100% active residency and a software state of P10. In Low Power mode, their frequency is capped at 1,056 MHz (67%), active residency remains at 100%, but with a software state of P4-P5.

powermetrics reports two software ‘states’ for the GPU, one that is requested, which for these renders is invariably P10 (P8 on the M3 Pro), and the other the state apparently applied. Although these appear to be some form of priority, with higher P numbers being higher priority, I’ve been unable to find any explanation.

For comparison, when running on the M3 Pro, active frequency was the maximum of 1,380 MHz (87% of the M4 Pro), 100% active residency, and software states requested and given at P8 throughout.

CPU and GPU power use

Perhaps as a result of many GPUs now using 200-1,000 W of power, we have come to assume that GPUs inevitably consume the lion’s share of power in a computer. While that may be true of many PCs, even of some Intel Macs, it isn’t true of Apple silicon.

Maximum power used by the GPU in any 0.1 second sampling period during these tests was 25.3 W, and measurements on M4 Max chips with 40 GPU cores suggest they can use a maximum of about 50 W. Any PC gamer with a GPU using so little power would hang their head in shame, yet performance of Apple silicon GPUs is by no means poor.

While power used by the GPU during heavy workloads can remain at 14 W or more for sustained periods, when performing scalar floating point calculations, CPU cores generally remain below that. However, vector and matrix calculations in CPU cores and possibly the AMX coprocessor can exceed the maximum for a 20-core GPU, at 33 W for NEON floating point vectors, and 36 W for floating point matrix multiplication.

Summary

• There are two different types of Power Mode in Macs. MacBook Pro models without M1 Max, M2 Max, M3 Max or M4 chips support an older Low Power mode that dims the display to extend battery endurance, but in Apple silicon Macs has no significant effect on their performance.
• New Power Modes are available in MacBook Pros with M1 Max, M2 Max, M3 Max or M4 chips, and Mac minis with M4 chips.
• High Power mode doesn’t alter performance, but makes fan strategy more aggressive to support longer periods of high power use.
• Low Power mode constrains the frequency of CPU and GPU cores to reduce CPU power to about 80% and GPU power to about 33%, so achieving substantial savings and less fan use, at the cost of impaired performance.
• M4 GPU cores achieve better performance over those in M3 chips by a combination of higher frequency and improvements in the core itself.
• Apple needs to correct terms used in System Settings, and in its documentation, which are currently misleading and confusing.
• It’s not clear why Low Power mode is only available in selected models and chips.

In this the second of the pair of articles showing paintings exploring the physical and optical properties of winter ice, I resume my account in 1883, after Impressionism had started to sweep across Europe.

The Norwegian artist Frits Thaulow was one of the Nordic Impressionists who met in Skagen, Denmark. During the 1880s he developed what came to dominate the paintings of his later career, optical effects on the surface of rivers. He painted this scene of Winter at the River Simoa in 1883. A lone woman, dressed quite lightly for the conditions, is rowing her tiny boat over the quietly flowing river, toward the tumbledowns on the other side. The surface of the river shows the glassy ripples so common on semi-turbulent water, and the effect on the reflections is visibly complex. The distant side of the river is also partly frozen, breaking its reflections further.

Thaulow’s Spring Thaw from 1887 captures perfectly the peculiar softness of such scenes in early spring, as the meltwater is still icy cold and ice remains around its edges.

Emile Claus’s dazzling view of a small group of skaters in The Ice Birds (1891) was inspired by a contemporary novella, and shows the flooded swampy area near Waregem when frozen over in winter. Claus draws a distinction here between the less reflective surface of snow, and the ice that’s richly coloured in the winter sunlight.

Another Norwegian artist, Jahn Ekenæs here demonstrates that even in the bitter Nordic winters, the washing still had to be done, and only one of the women in his Women Doing Laundry Through a Hole in the Ice (1891) is wearing anything on her hands. Broken blocks of ice in the right foreground demonstrate its thickness, although that’s barely adequate to support the horse and sledge in safety.

One of Lesser Ury’s more conventional motifs, his beautiful pastel of Tiergarten in Winter from 1892 shows the large park to the west of the Brandenburger Tor in Berlin, with its blue river frozen over and a good covering of snow.

Hans Andersen Brendekilde’s Melting Snow from 1895 is a wonderful depiction of a harsh winter in the country. An elderly couple are doing the outside jobs in typically grey and murky weather, in the backyard of their thatched smallholding. He has walked down to fetch a pail of water from a hole in the ice on the river. Around it the ice is discoloured from contaminants in the water and surely not fit to drink.

During the early New Year of 1898, Eugène Jansson painted Riddarfjärden. A Stockholm Study from his studio, with ghostly blue ice covering much of the water below. A small steam vessel is making its way along the ice-free channel towards the foreground.

When Lovis Corinth lived and worked in Berlin, he too painted the occasional urban landscape of the city, including this wintry Ice Rink in the Berlin Tiergarten from 1909, where Berliners are skating on frozen lakes in the city’s zoo.

A couple of years later, at the other end of the earth, Edward Wilson’s watercolour of The Great Ice Barrier – looking east from Cape Crozier was painted in the austral summer, on 4 January 1911. This shows small groups of penguins on the ice cliffs at the edge of the Ross Ice Shelf in the Antarctic.

Back in the Northern Hemisphere, the young Canadian artist Tom Thomson painted After the Sleet Storm in his studio during the winter of 1915-16, from oil sketches he had made in front of the motif. This shows the beautiful effects not of frost as such but of sleet frozen onto the canopies of birch trees, in the winter half-light. Pale pinks and blues shown on the trees here are reminiscent of spring blossom.

Thomson’s Snow in October (1916-17) is another well-known studio painting that Thomson made the following winter. Its fine geometric reticulations of frozen white canopies are a surprise, and an opportunity for the artist to use subtle colour and patterns in its shadows.

It’s high time to return indoors and warm up with a glass of mulled wine.

Everyone knows that January, the first month of the New Year, is named after Janus the Roman god of transitions. There are a couple of problems with that, as neither the Romans nor the Greeks started the New Year in the middle of winter, not when they could help it. Although it’s true that the Romans named the first month of the year Ianuarius, according to some ancient almanacs that wasn’t in honour of Janus, but of Juno. The more modern assumption that January, now a winter month, was named after Janus, classically depicted as a duality, makes a more plausible story. Janus characteristically has two faces on a single head, one looking backwards to the old year, the other looking forwards to the new: Ianus Bifrons in Latin.

So he appears in Anton Raphael Mengs’ wonderful fresco in the Vatican’s Camera dei Papiri, The Triumph of History over Time (1772). You’ll no doubt recognise Father Time with his long grey beard and scythe in the foreground, behind whom History is busy keeping records. She looks up to the fresh new face of Janus, as the old face looks away to the right.

This New Year I’d like to cast us back to September 2016, when macOS 10.12 Sierra had just been released, six years after Apple had released the iPhone 4, the first with its own A4 chip. Just four days before Sierra, Apple released the iPhone 7, with its two P and two E cores, making it the first Apple silicon design to adopt Arm’s big.LITTLE architecture. Maybe some engineers have been working on a prototype Mac using an A11 (to be released in the iPhone 8 the following year), and the specifications for the first generation of Arm-based Macs are being finalised.

To get from Sierra running on Intel 4-core Skylake processors to macOS 11 running on 4-core M1 chips, there’s a long list of changes to be made, including:

• a modern file system to replace HFS+, designed for SSDs, with support for containers, volumes, sparse files, snapshots, and more;
• running 64-bit code throughout;
• macOS to run from a signed system volume on a mounted snapshot verified by a tree of hashes;
• replacement macOS installers and updates to maintain macOS in the SSV;
• a firmlinked Data volume to be writeable by the user, with FileVault implemented using hardware encryption;
• a secure enclave;
• a fully secure boot process in custom firmware without using EFI.

Engineers have already been working on those, and the first release of the new file system, APFS, is intended for the following year, when intermediate hardware based on the A10 in the iPhone 7 will be released as the T2 chip, providing a secure enclave, hardware encryption and a firmware development platform. The problem now is how to complete the rest of the transition, so enabling the first Apple silicon Macs to be released by the end of 2020.

Although four years might seem a long time, here’s a timeline for those changes:

• 2017: APFS release, first T2 Macs.
• 2018: completion of major APFS features, transition to 64-bit code.
• 2019: 64-bit only, intermediate boot volume group without SSV.
• 2020: SSV and boot volume group, replacement install and update, firmware for a full hardware release late in the year.
• 2021: improved efficiency in macOS updates, paired Recovery volume.

And that’s exactly what happened from macOS 10.13 High Sierra to 12.0 Monterey.

However and whenever those changes were to occur, it was going to be a demanding period for Apple’s engineers, third-party software developers, system administrators and users alike. Was there an alternative that could have completed the same transition at a slower and more comfortable pace?

Merging the changes for any adjacent years would have resulted in at least one upgrade that would have made impossible demands. For those who have wanted major versions of macOS to be released every two years, the consequence would have been that macOS 11.0 would have been released just a few months ago, and only now would we be trying out our new M1 Macs. The next time that someone wishes that macOS had been upgraded at a slower pace over those years, remind them how that would have delayed introduction of Apple silicon Macs by around four years.

With that, it’s time for Janus to swap faces, and look forward to the coming year.

Now we’re into January, the proper winter weather should be here. It’s time to don our duvet jackets, woolly hats and mittens and go out to see lakes and rivers transformed from their usual liquid state into solid ice. This weekend I tour the world in search of those paintings seizing this opportunity to explore the physical and optical properties of ice in nature, in this article up to the advent of Impressionism in the late nineteenth century, and tomorrow from then until the First World War.

Among the best-known of winter paintings, Pieter Bruegel the Elder’s Winter Landscape with Skaters and Bird Trap (1565) was copied repeatedly by his son Pieter, and by others in the family workshop. At least sixty copies are believed to have been made, one dated as late as 1626, sixty years after the original. This is among the early landscapes showing people walking or skating on a frozen river, and to the right of the canoe-like boat a small group is engaged in the popular game of colf. As is usual with many rivers, the ice here has a pale ochre tinge.

Aert van der Neer’s beautifully-lit Sports on a Frozen River (c 1660) includes several playing colf, an antecedent of golf that was also played during the warmer months, but was most distinctively played on frozen rivers and canals. The reflection of the low sun on the ice is particularly well shown here, giving the ice a polished sheen.

Scenes of frozen rivers and canals became increasingly popular during the Golden Age. Although Aelbert Cuyp doesn’t appear to have painted many of these, his Ice Scene Before the Huis te Merwede near Dordrecht from about 1655 is among the finest. Notable here are his foreground reflections on the mirror-like surface, and the wonderful sky with its warm clouds. The castle seen here was built to the south-east of Dordrecht in the early fourteenth century, and ruined a hundred years later.

Jacob van Ruisdael painted several seasonal landscapes, including two similar versions of Winter Landscape (c 1660-70). This is the Mauritshuis version, which is perhaps slightly preferable to that in Birmingham, Alabama, although both show similar finely detailed frost on the trees and vegetation, heightened by the darkness of the ice and sky.

Caspar Wolf painted this finished version of The Geltenbach Falls in the Lauenen Valley with an Ice Bridge in about 1778, from what appears to have been a sketch made en plein air. Although not particularly early for a plein air oil sketch, given the logistic problems associated with working outdoors in oils in this remote rural location, it’s quite an achievement. These falls were little-known at this time, but when nearby Gstaad became an internationally-known spa town in the nineteenth century, they were added to many tourist itineraries.

In 1839, François-Auguste Biard travelled with a French expedition to Spitsbergen and Lappland. The only painting from this expedition that I’ve been able to locate is this view From Magdalena Bay, Spitsbergen, apparently made in oils in front of the motif, despite its considerable detail. Although much of the sea is shown unfrozen, there are several small bluish icebergs and ice covering the shallows along the coast.

Two years later, Biard completed Magdalena Bay; View from the Tombeaux Peninsula, to the North of Spitsbergen, Effect of the Aurora Borealis. This was exhibited in the Salon of that year, and again at the Exposition Universelle in Paris in 1855. Lit by the eery light of the aurora is a small group of survivors, who are not mentioned in the title. Five rest on the snow in the foreground, all but one apparently already dead, and there is wreckage down among the heavier sea ice behind them. One person’s footsteps lead up to the viewpoint of the artist.

Johan Jongkind’s fine View of Maassluis in Winter from 1848 is a good example of his early work. Following the long tradition of landscape painting in the Netherlands, he sets his horizon low and paints a wonderful winter sky. Underneath that, the locals are skating along a frozen canal, which has both rutted areas and some that are more polished.

Jongkind revisited this theme in 1873, when he painted this Canal in Holland in Winter with his mature rough facture.

Although now exceptionally unusual, during the nineteenth century and earlier the River Thames in London often froze solid for long periods most winters. This afforded James Whistler the chance to paint The Thames in Ice in 1860, with its monochrome relieved only by earth browns. It’s thoroughly painterly, and its details appear to have been sketched in quickly, suggesting it might have been painted in front of the motif. However, it’s a relatively large canvas, and Whistler is known to have painted from memory in the studio.

In 1869, the marine artist William Bradford travelled on board the steamship Panther on an expedition to Greenland. An Arctic Summer: Boring Through the Pack in Melville Bay (1871) shows their ship working its way through pack ice close to the west coast of Greenland. Melville Bay is a huge bay on the island’s north-west coast, and an important area for whaling fleets in the nineteenth century.