Tag: Design history

Washington Sabatini’s impressive calculator

March 19, 2021 / Nathan Zeldes / 0 Comments

Here is one impressive calculating device: Washington Sabatini’s reinforced concrete calculator.

Washingtron Savbatini's H 39 reinforced concrete slide rule

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 the device, as is the celluloid cursor overhanging the largest ring. The movable rings are rotated around the center of the device by use of the prominent crank handle that spans its radius.

For full details, and a worked out example of how to calculate the dimensions of a concrete beam under specified parameters, see this article on my History of Computing site.

Enjoy!

Lalanne’s glass slide rule

May 15, 2020 / Nathan Zeldes / 0 Comments

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!

Jacob Zedak’s wooden slide rule

April 10, 2020 / Nathan Zeldes / 0 Comments

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 made of metal, and later of plastic. Yet Jacob Zedak chose wood as the raw material for his take on these disc-like calculators; and he used plywood, which wouldn’t be used even in a linear rule.

Circular slide rule by Jacob Zedak

Read all about this unusual device, and about Zedak’s other products, in this new article on my History-of–Computing site.

Enjoy!

The Data Scaler Proportional Rule

March 3, 2020 / Nathan Zeldes / 0 Comments

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.

The Datascaler Proportional Rule and the Gerber Variable Scale

This device is a clone — a direct knock-off — of Gerber’s elegant invention. Close inspection shows the small differences in design and manufacturing quality that usually accompany such cloning.

This article examines the details, and uncovers who made this device and under what circumstances.

Check it out!