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Commonsense design blog
The Good, the Bad and the Ugly of everyday product design
Here is one impressive calculating device: Washington Sabatini’s reinforced concrete calculator. This complicated circular slide rule is one of the largest items in my collection. It comprises ten concentric aluminum rings covered with complicated scales and pointers. The rings are all movable except for the second largest; that one is fixed to the body of … Read more
The photographic camera is one of the great inventions of the 19th century, and is quite a simple idea: take a light sensitive surface, put a lens in front of it, add the ability to control exposure time and aperture, and you’re all set. And for more than a century, that’s what cameras were all … Read more
The Tavernier-Gravet company was France’s premier scientific instrument maker at the end of the 19th century, and it stayed abreast of the latest developments in slide rule design and production when it entered the 20th century. In this this new article on my History-of–Computing site I illustrate some of their problems and solutions as they … Read more
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