nzeldes When my kids were at school they were taught addition with colored wooden rods. Well, a century earlier two innovative Frenchmen – Henri Genaille and Edouard Lucas – invented a system that does rapid multiplication and division using much more sophisticated rods, and I have in my collection a box of these ingenious calculation aids. … Read more
Monsieur C.-F. Martin was a retired naval clerk, and evidently he had developed a great love for painstaking calculation. Just see this 100×100 multiplication table and units conversion tables he published at the beginning of the 19th century, to help his countrymen deal with the switch from the old Empire weights and measures to the … Read more
So what do you do if you want to give a computer to every child, and the computers of your day are made of expensive boxwood? Why, you invent a cheap slide rule made of Glass! Leon Lalanne did, in 1851. Read all about it here!
What’s so special about a wooden slide rule, you ask? And indeed, for most of their 3½ centuries of existence — until the arrival of plastics — the material of choice for making slide rules has been wood… but that is the case with straight slide rules. Circular slide rules, by contrast, were almost exclusively … Read more
The Gerber Variable Scale, described here, is a thing of beauty and elegance, admirable for its ingenuity and craftsmanship. It is also a “one of a kind” device, or so I thought until my unexpected sighting on eBay of the “Proportional Rule” made by the Data Scaler corporation of Westfield, Massachusetts. This device is a … Read more
A few years ago I sighted on eBay a set of three German circular slide rules of the Controller brand. There was a big one, 20 cm in diameter; a midsized one 11 cm across; and a small one at 7.5 cm. They all looked pretty much the same except for their sizes, and this … Read more
The circular slide rule developed around 1920 by Jules Arnault and Louis Paineau comes in a wooden frame, to give it durability and ease of use; but it is so pretty you can – and I did – hang it on your wall! Aside from being pretty, this is an ingeniously designed and very well-made … Read more
Here is a photo of the Jerusalem central bus station, a large blocky building at the entrance to the city. So, maybe it’s just me, but whenever I see it I get reminded of a mathematical construct – the Menger Sponge, a three dimensional fractal. Judge for yourself: OK, OK, the bus station is not … Read more
One of the strangest slide rules in my collection, this ingenious Italian device from the 1950s allows you to factorize numbers into their prime factors in an instant. Just move the “Bull’s eye” cursor to the number you wish to examine and the crisscrossing lines and symbols line up to give you the answer. Check … Read more
I was at this coffee shop and saw the two machinettas. Of course I didn’t buy one – as coffee lovers, we have all the machinettas we need at home – but I did notice how the pair represents two different solutions to a small but important design bug that the classic machinetta had subjected … Read more
