Scarcity

During the COVID-19 crisis we were suddenly confronted with scarcity of mouth masks and ventilators. 

Has there ever been a scarcity of slide rules?

Yes: during the Second World War. 

That scarcity had several causes.

Materials

In the Netherlands the import of slide rules was limited, but fortunately there were locally made ALRO calculation disks.[1]  ALRO, however, had difficulty obtaining aluminium, so the calculators were temporarily made of zinc.[2] 

Figure 1: a wartime-time ALRO (left) and a post-war ALRO (right) on postal scales.

In the USA, too, the supply of materials for slide rules was problematic, so Pickett made cardboard slide rules for a while, the "Demonstrator".[3]  Wooden slide rules were originally made of wood that had to be a few years old, so stocks could run out later in the war. [4]  In Germany a shortage of materials (probably) led to the development of a slide rule made of a kind of plywood.[15 In the USA a 5 inch slide rule including scale was moulded out of a thermoplastic.[6] In Germany the Logarithmal, a grid-iron slide rule, was delivered even without a cursor due to a lack of materials.[7] 

Production capacity 

Manufacturers of slide rules and related articles were also asked to make instruments for the army. At the beginning of the war Stanley indicated in his catalogue that production was mainly aimed at the "Services", that the range for regular customers had been reduced and that there could be delays in the delivery of articles.[8]  In Germany, it was strictly regulated which company was allowed to make which type of slide rules, often specifically for the army.[9]  In Germany, it was strictly regulated which company was allowed to make which type of slide rule, often specifically for the army.

In the USA, Keuffel & Esser gave a smart twist to the situation (figure 1): "Defense is asking for more slide rules than we can make, but we are in the process of increasing production capacity within 4 months. In the meantime, we are lending students a simple slide rule that can later be exchanged for a real K&E."[10] A $1 deposit was required. One of these slide rules, a K&E 8858 10" Mannheim, is still in the Hoboken Historical Museum (figure 2).[11]  The problem here was not so much a shortage of materials, but rather inadequate production capacity. This problem was exacerbated by the fact that spare parts for the machines used to make slide rules were already scarce.[12]  The 4-month period K&E maintained in 1941 was a bit optimistic. Even in 1944 there were still too few slide rules in the USA, according to an advertisement in the student magazine of MIT (figure 3).[13]  Dietzgen and Post tried to fill the gap with "war-time" models, such as the Dietzgen 1769P Federal, which was made from 1941 to 1946.[14]  Post involved the 1452-D and 1446-D models of Lawrence and/or Charvoz-Roos.[15] 

Figure 2: K&E loan slide rule

Figure 1: Slide rules are drafted

Figure 3: Advertisement of the MIT (1944).

Post-war

Even after the Second World War a shortage of slide rules continued to exist, for example in the United Kingdom, where after the war the import of slide rules from Germany did not start. This provided a good opportunity for the English slide rule industry to flourish[16]  although the prices of German instruments were extremely low due to low labor costs during the German reconstruction.[17]  Material shortages also led to inventive solutions in Germany, as was probably the case with the (eastern) German ALCU slide rule, made of paper and glass.[18] 

Don't get stuck with that stick

In the USA after the war many ex-soldiers went to study using the GI-Bill, which led to more demand for slide rules than the established firms could handle. In 1947, K&E was only able to supply the University of Pittsburgh bookstore with 155 slide rules, and Dietzgen with only 6, while more than 250 ex-soldiers  studied engineering in Pittsburgh and the bookstore had ordered 1000 slide rules. When poorer quality slide rules were sold out of necessity, with scales that were printed (such as those of Lawrence and Charvoz-Roos), it led to the student action "Don't get stuck with that stick".[19] A slogan that surely will appeal to elder KRING-members trying to de-collect.

Hungarian solution

Hungary also suffered from a post-war shortage of slide rules, which professor Géza Pattantyús-Ábrahám[20] solved in 1946 by asking a carpenter to make  wooden blanks. He pasted a photograph of a foreign slide rule on the blanks and added a folded celluloid tape as a cursor. These slide rules were sold to students for HUF10 (about $1 at the time).  A regular slide rule would cost HUF 200 to 300.

References

An earlier Dutch version of this paper has appeared in MIR 81, May 2020.