Debian Bookworm - Release Critical Bug Status

Debian Bookworm has been "frozen", meaning it gets no package updates except bug fixes (boring times for a Testing user!). Time to have a look at the bug graph again. Here it is (Bookworm in green). Currently there are 393 release critical bug to be squashed before it is released later this year.

Release-critical bugs status.

Claws Mail

Why use Claws Mail?  (I'm asking that question in Linux, but it's available for Windows too.) Well, when I looked at email clients that worked on my Debian XFCE installation, I found Thunderbird using 600MB of RAM and Evolution using 300MB. Even GMail open in a browser tab uses 300MB. Claws Mail, on the other hand uses 73MB of RAM:

This would certainly make it useful on an old computer with little memory available, but doesn't it look like some relic from the Windows 95 era? No, it supports GTK3 and at least in Debian some nice themes are available. Still old school but looks OK:

So here is the full list. Why use claws mail?

• Lightweight, low memory usage, but still full featured. Does filtering and processing. Fits in to the XFCE desktop well. In Gnome I use Geary for casual emails and Evolution for more serious use, but Claws does both.
• Supports GTK3 and has a wide range of themes available, from old school to modern.
• Supports OAuth2, the authorisation protocol used by GMail and other email providers now.

There are also some features that Claws Mails does not have that may be reasons not to use it. On the other hand, they may be features you do not need or want:

• Push emails are not a feature. You have to wait until Claws Mail check for new mail, at whatever interval you set.
• New email desktop notifications from GMail don't work because GMail doesn't mark any messages as 'New'. There is a patch available to change behaviour to notify for unread messages, but it involves compiling Claws from source code.
• Emails are displayed by default as plain text, not HTML. There is a plugin to switch to HTML view, but if you prefer the formatting, fonts and background images of HTML mail, Claws is probably not for you.
• Claws Mail doesn't do the modern tiled subject column that Geary does. Layout is strictly old school.

So there you have it, a lightweight, minimal (but still powerful) email client to keep open if you don't like web mail or the size of some other email clients, and are not put off (or in fact enjoy or want) basic email features.

 

The secret of the Bessler wheel

Recently I wrote about a modern "perpetual motion" machine, a bicycle wheel that revolves for years without any apparent source of power. Of course it is not really a perpetual motion machine. It was built by a scientist as a challenge for those who saw it to work out how it was powered,  a challenge that 40 years later still baffled Adam Savage in a YouTube video.

I was fascinated by the reference in that video to the Orffyreus wheel, a similar machine from the 18th century. The name was code for the real name of the inventor, Johann Bessler. His wheel (or wheels, actually, as he built several of different sizes) would start moving from stationary with a slight push and would run at 25-50rpm for up to 54 days without any obvious energy source. They could do real work, lifting 5-40lb, depending on the size. Even today there is speculation that he may actually have discovered a source of perpetual motion.

I think the secret is quite simple however. The machine had to have a source of energy, and how would you power a machine like this? Gravity. There were clocks powered by gravity from the period like this one:

A heavy weight on a rope wound round the cylinder visible in the picture would have rotated the cylinder, with the torque converted to movement of the hands by a train of gears. It was obviously situated in a tower or high up on the face of a building or in a high space.

A simple falling weight would not work to power a wheel because it could not pass through the axle. Most probably there was a weight (or weights) attached to a shaft around the axle, powering the mechanism again through a gear train.  A couple of large lead weights falling from the top of the machine around the inner circumference towards the base could have powered a hollow wheel on bearings for many days, or easily contained enough energy to explain the work the machine did. (Yes, they did have bearings in the early 18th century.)

So there you have it. The wheel was a clock. There are actually a couple of very large clues: the pendulum on the front of the wheel controlling an escapement, and the fact that Bessler was an apprentice watchmaker.

Some witnesses of the Bessler machine stated that they could hear falling weights in the wheel, leading to speculation that it was a weighted wheel machine. Such a machine can work, if there is an input of energy, giving weights at the top of the wheel a nudge upwards (and increasing their potential energy). The power source I have described could have been used to do this.

I suppose it's possible that with a complex mechanism of large weights and smaller weights moving in the machine Bessler genuinely thought he was getting something for nothing and failed to realise he was supplying the machine with potential energy in setting up the machine in a state where some of those weights could fall over time, supplying the machine with the kinetic energy it needed to keep running. I'd somehow rather believe that he wasn't an outright fraud.