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Power operated slide rules.
Single-hand operation
Single-hand operation
When using a slide rule, you really need three hands: two to manipulate the rule and one to write down the result. This incompatibility with the human anatomy could be solved by putting your slide rule in a desk stand. Some "normal" slide rules like the Keuffel & Esser 68-1892 Prep K-12,[1] were issued with a stand in which the slide rule could be laid down. Often this had more a display function than a utilitarian one.
The Keuffel & Esser N-4096 Merchant slide rule has two strong feet and a knob on the slide so it can be operated with one hand (Figure 1). This 20 inch slide rule appeared in the K&E catalogs from 1927 to 1969, so it will have met some demands. Large cylindrical slide rules, like the Thacher and LOGA's, allow basically one-handed operation. Also some disc calculators, such as the famous ALRO have a desk stand making them suitable for one-handed operation. The giant Smith-Davis Balance Calculator[3] is operated with one hand and one foot and even has a writing desk.
Figure 1: K&E N-4096 Merchant slide rule with single hand operation[2]
But it can be even more comfortable
But it can be even more comfortable
In 1953, Paul J. Toien from Los Angeles got a U.S. patent[4] for a cylindrical slide rule with one-hand operation. As a bonus, he provided this thing with a motor drive (Figure 2). The motor and various mechanical couplings were controlled with a switch box that was attached to the cylinder with a long cable, allowing the user to put the cylinder in a prominent place and still operate the instrument. The device had to be connected to the mains, and that is one downside.
Toien's patent refers to a U.S. patent[5] by J.L. Taaffe from 1951 that describes a computing device with logarithmic scales on strips that were wrapped on rolls (Figure 3). This device is also powered by an electric motor, but the controls are on the device. Toien indicates that this is less comfortable than a separate control unit.
In 1968, a patent[6] was issued to George R. Hunt Texas for an electrically driven linear slide rule. He did not apply the electric drive for one-hand operation, but because his slide rule was to be used in education and would therefore be very large. The patent shows that this slide rule has a "remote control" (Figure 4). The instrument has three motors: one for the cursor, one for the slide, and one for turning the rule. Hunt explains several methods for moving the cursor and slide, including pneumatics. You'd wish every math teacher had one!
Figure 5: Article in Popular Mechanics (April 1958) An April fools' joke that finaly made it into a patent??
In 1962, the German slide rule manufacturer A.W. Faber-Castell also patented a motor driven slide rule, with both education and advertising in mind,[7] see Figure 6. In the same year, Ronald Pasqualini and Philip F. Hudock, two MIT students, demonstrated a remotely operated classroom slide rule.[8] Their control device looked like a slide rule, which seems better suited for education than Hunt's push button box.
Much later, Cliff Stoll had made his own electric slide rule operated by push buttons. You can see it in action!
Figure 6: Faber-Castell motorized slide rule (Schönner patent DE1128193)
Electromagnetic coupling
Electromagnetic coupling
There are also electric logarithmic calculators without a motor. Dr. Herbert Fuß described in a German patent[9] from 1927 a device with logarithmic scales on rolls in which only the coupling between the rollers is electro-mechanical. The rotation of the axles is carried out by hand (Figure 7).
In a recent U.S. patent[10] Kato Shigeyoshi describes a logarithmic calculating device with wheels (Figure 8), in which push-button A couples the wheels electromagnetically. He also provided the unit with indicators B for the magnitude of the numbers on the scales (1,10,100 ...). The magnitude is set stepwise by an electromagnet D which is activated by push-button C, but also by a complete revolution of the corresponding scale wheel E. This is an electromechanical decimal indicator.
Figure 7: Calculating device with electromechanical couplings according to Fuß (patent DE471113)
Figure 8: Calculating device with electromechanical couplings according to Kato (patent US3473732)
Strange patents
Strange patents
I do not know if any of these inventions was ever put into production. It seems unlikely that they were used as stand-alone slide rules, but perhaps they were parts of certain instruments. A patent[11] assigned to Beckman Industries for a "Calculator for monochromator dispersion" shows a computing part of a monochromator which is very similar to Hunt's slide rule. The archives of the patent offices are full of patents on inventions that are never realized. Yet it is interesting to see these patents. They indicate where the practical problems were encountered and how these problems could be solved according to the state of the (former) art. We must bear in mind that the images and descriptions in the patents are not intended as blueprints and manuals. They can therefore be further from reality than we expected at first sight.
Notes
Notes
See “Lack of space", MIR 46 (Dec. 2007), page 13.
Paul J. Toien, “Slide Rule”, US Patent 2650762, Sep. 1, 1953.
John L. Taaffe, “Slide Rule”, US Patent 2527776, Oct. 31, 1951.
George R. Hunt, “Powered Slide Rule Assembly”, US Patent 3406900, Oct. 22, 1968.
Willy Schönner, "Rechenschieber für Unterrichts- und Reklamezwecke", DE1128193, Apr 19, 1962. Thanks to David Rance for suggesting this patent.
MIT Technology Review, March 1962. p.22
Herbert Fuß, “Logarithmischer Rechenapparat”, DRP 471113, Feb. 24, 1927.
Shigeyoshi Kato, "Calculator", US Patent 3473732, Oct. 21, 1969.
Maoyeh Lu, “Calculator for monochromator dispersion”, US Patent 3610758, Oct. 5, 1971.
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