Ex Urbe

Two quick announcements, then something fun to share.

First, comments were disabled for a little while.  Now they are enabled again.  Apologies to everyone who wanted to discuss Beccaria – I hope you still want to discuss him, and now you can.

Second, people have been reporting trouble subscribing by RSS.  I have investigated, and it seems that, while Firefox, Explorer etc. are fine, Chrome won’t do RSS (for this site or any site) unless you install a Chrome extension for RSS.  Googling “Chrome extension RSS” will supply a variety of equally viable methods.  However, for those who are struggling with RSS and can’t get it working, I have created a mailing list which you can register for in the right-hand sidebar.  Whenever I make a new post I will e-mail the list to alert people.  I recommend, however, that you use RSS instead of the mailing list if you can, because RSS will definitely alert you without, whereas the mailing list is hampered by my ability to remember to do it.

Meanwhile, I will take this opportunity to present another of my favorite objects in the Florentine Museum of the History of Science (aka. Museo Galileo): the Noon Cannon.  This is a strange variant on a sundial.  A tiny cannon, well under a foot long, is mounted outside, ideally in the gardens of a grand estate.  It is fixed in place on a stone slab, with a lens positioned above it.  At precisely noon each day, the lens focuses sunlight onto the canon, heating up the powder charge and making it go off.  If every morning you load the cannon with a little bit of gunpowder, then you will be reliably alerted to noon by the sound of a small explosion from your garden.  The effect is sort-of like a water clock except, instead of tranquil trickling and the tap of wood on stone, there is a ka-boom.

I think the specimen in the museum is probably from the Eighteenth Century, possibly the Seventeenth, but I can’t remember off the top of my head.  Of course, no one in our era can see a Noon Cannon and not instantly think of its potential uses in an old-fashioned murder mystery.  Simply put shot in the Noon Cannon along with its daily charge, lure the victim to the garden at the specified time, and you can be miles away having an alibi while the Noon Cannon does the rest.  “The Colonel put real shot in the Noon Cannon?  How dastardly!”  The killer could even mess with the lens to make it fire at an unexpected time, then play around with other sources of a substitute noise, a hunting rifle or a champagne cork to simulate the 12 PM shot… it writes itself…