| Name and Model Number | The Mechanical Engineer Calculator -- 3 Sizes |
| Country of Origin | England, Manchester (distribution), Swiss made |
| Date of Manufacture | ca. 1900 |
| Front Scales | L, A, C (2 circles), S |
| Back Scales | none |
| Scale Length | 5" to 7" |
| Type of Rule | Watch Type |
| Construction | Metal case with glass front, rotatable paper scales, and fixed and movable cursors. Scales rotated by main stem and cursor rotated by side stem |
| Area of Use | Generic |
| Comment | For basic mathematical calculations.
NOTE: Sizes vary. See the 3 individual detailed views and descriptions for these calculators ... Large, Mid Size, and Small. |
| Rarity | RR |
| Donor | Collection of Dr. Paul J. Tarantolo Jr. |
| Match Number | 64 |
| 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. |