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
This new article on my Possibly Interesting site is strictly for radio amateurs and other geeks: a photo-essay depicting circuit and construction details of the SSB transmitter I’d built a long time ago. What makes it interesting (other than the nostalgia of vacuum tubes, that is) is the prevalence of improvised, scavenged and military surplus … Read more
This is Jaen-Antoine Lafay’s Hélice a Calcul, a rather unusual logarithmic slide rule. But Lafay himself, its inventor, was just as unusual, not to say quirky… a fascinating lone innovator waging war on an indifferent world. To illustrate, here is a section from Lafay’s marketing brochure: Oh, routine! What wrong do you not do, firstly … Read more
In the days before GPS, Google Maps and Waze, people used maps; and to figure how long it would take to get from A to B on a map, you could make excellent use of a Marsch-Zirkel, or march compasses… like the lovely device described in this new article on my History of Computing exhibition. … Read more
The Baines slide rule is one of the most unusual ones in my collection, because of the metal contraption on its back that moves all its parts in unison. Here it is: This slide rule was designed by a British civil engineer from the Punjab; it is used to calculate water flows and pressure drops … Read more
These days the preference for shoddy, cheap, use-and-discard products is all over the place. Here is an example: This sorry street sign in Jerusalem has taken on a very “artistic” look – because it is made from a blue layer of stick-on plastic sheet over a metal plate. Over time the plastic started to shrink … Read more
Some of the most fascinating items in my History of Computing collection are the one-of-a-kind, undocumented ones. The latest such addition to the collection is a calculator hidden in a book-like case, that has no mention anywhere that I could find. This is Charles Cornell’s F.24 aerial photography planning calculator, and you can read all … Read more
This Barometer was made in Florence some 100 years ago, and served my late grandfather, first in Italy, then in Israel; it ended up on my wall, a family heirloom to delight the heart of any engineer. It is a large (23 cm across) Aneroid Barometer, an instrument to measure atmospheric pressure by means of … Read more
Form follows function; but often both must follow the available materials. Consider the image that comes to mind at a statement like The great king raised his mighty sword to smite his enemies. Surely, you imagine a sword structured something like this: Photo courtesy Søren Niedziella, shared on flickr under CC license. This, after all, … Read more
For some reason, inventors in the first half of the 20th century thought that incorporating a slide rule into a mechanical pencil was a great idea. In reality, these combination devices were of dubious utility, gives their low precision as calculators… but they are certainly ingeniously designed. I describe three of them, including one extremely … Read more
