Cylindrical Slide Rule Calculator By Loga, Switzerland.

The Loga Company made this slide rule in Switzerland probably during the 1920’s under the registered patent of Daemen Schmid from Zurich. It consist of a paper-faced aluminum cylinder, 59 cm long X 16 cm diameter, and a sliding grid cylinder 32 cm long. The whole is mounted on an oak frame and protected with an arched oak cover. The total length including cover and handle is 69 cm (27 inch). In this slide rule, 1 log unit (from 100 to 1000) is divided along 60 consecutive and parallel scales. There are 60 scales printed around the circumference of the inner cylinder. On Each scale the numbers drawn are logarithmically divided (scale #1 starts with 100 and scale #60 ends with 1000). Since the actual length of each scale is 50 cm, the total length of all scales sums up to 30 meters. This total is therefore divided into 1 log unit only, which makes this slide rule very sensitive and accurate. The outer grid cylinder is only 25 cm long with 60 parallel scales as above. In a small area on the right hand side of the paper, the printed numbers were erased; otherwise the condition is good.