| Name and Model Number | Tröger Cylindrical Slide Rule |
| Country of Origin | Germany |
| Date of Manufacture | c. 1920 |
| Front Scales | 20 sections; 2/3 of length repeated |
| Back Scales | Slide scales: 10 sections; no length repeated |
| Scale Length | 1.5 m |
| Type of Rule | Cylinder |
| Construction | Wood with gridiron type scales printed on paper |
| Area of Use | Generic |
| Comment | Maker's name not marked, but DRGM 639848 was granted to K. Emil Tröger in 1915. Scale layout is unique to Tröger cylindrical slide rules. On other Swiss, German and American cylindrical slide rules each succeeding section repeats half of the previous section. Succeeding scales on the Tröger, repeat 2/3 of the previous section. The result is that the sliding sleeve has half the number of scales on the cylinder instead of the same number of scales.
Use could be textile industry in eastern Germany. |
| Rarity | RRR |
| Donor | Collection of Ed Chamberlain |
| Match Number | 195 |
| Thumbnail (Click Picture for Details) |  |
| In conjunction with our 'donors' we assign a rarity rating to each item, based on the system devised by Herman van Herwijnen |
| (1929 - 2004), renowned Dutch collector, author, and creator of Herman's Archive, a collection of 5,000 slide rule images on CD. |
| • RR = Rare - 1 of 25 collectors has one; it may take a year to find an example in the marketplace. |
| • RRR = Very Rare - only a few known to collectors; may be several years before it comes up for sale. |
| • RRRR = Extremely Rare - a museum piece; unlikely that an example will come up for sale. |