| Name and Model Number | Gravet - Lenoir 25 cm Règle à Calculer |
| Country of Origin | France |
| Date of Manufacture | c. 1851 - 1866 |
| Front Scales | A [ B C ] D |
| Back Scales | S L T |
| Scale Length | 25 cm |
| Type of Rule | Slide Rule |
| Construction | Closed frame boxwood, no laminate. No beveled edge. Chisel cursor missing. |
| Area of Use | Generic |
| Comment | Marked "GRAVET LENOIR 14 R. CASSETTE, PARIS". Address, maker and scale set dates this slide rule to 1851 to 1866.
|
| Rarity | RRR |
| Donor | Collection of Ed Chamberlain, USA |
| Match Number | 145 |
| 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. |