File:Loga Calculator Model W. 10 m. (History) (2022-11-28 by Kecko).jpg

Heinrich Daemen-Schmid emigrated from Germany to Zurich, Switzerland, and produced these cylindrical slide rule calculators with the Loga Calculator company from 1900. A patent of Julius Billeter is also indicated on it. However, the connection between the two remains unclear. The Billeter family believes that Heinrich Daemen-Schmid was once an employee at Billeter. The Daemen family doesn't know about it. Both claim to be the inventors of this calculating machine, which is not true. It has been mentioned before in 1888 and has been developed and improved.

The indication of the meter length refers to the total length of the individual stripes on the cylinder. The longer, the more exact the calculations. There were models of 1.2 m, 2.4 m, 7.5 m, 10 m, 15 m and 24 m. The 24 m type was the most accurate slide rule in the world with an accuracy of 5 to 6 decimal places, and cost 1921 Fr. 1000. A simple 1.2 m hand model was available for Fr. 110. There were not only different sizes, but also different types for specific business areas. For example, versions for simple arithmetic tasks, craft businesses, triangular calculations for geometers or finance. Around 28 different versions were available. I could not assign what purpose the type shown in the photo was for. It must be one of the older ones. Between 1900 and 1935 firm of Heinrich Daemen-Schmid manufactured approximately 30,000 cylindrical Loga-Calculators. Of the largest 24 m specimens, three to six are believed to have survived. In 1912 the device was also patented in the USA. International banker Jacques Kayalaff purchased one of them around 1925 for $500. In the 1930s, the production began to change from cylindrical slide rules to disc slide rules, and in 1979 the company was dissolved.

The first electronic pocket calculators, which came onto the market 1970 in Switzerland, only mastered basic arithmetic operations and cost over CHF 500. But that marked the end of the slide rule age. The noisy electro-mechanical calculating machines for basic arithmetic survived a little longer. Switzerland, November 28, 2022.