| Name and Model Number | Lejard Surveyor's Slide Rule (ETS) |
| Country of Origin | France |
| Date of Manufacture | c. 1900 |
| Front Scales | Cos/Sin [ Cot/Tan Nom/Dist ] Prod/Nom |
| Back Scales | None |
| Scale Length | 33 cm |
| Type of Rule | Slide Rule |
| Construction | Heavy stainless steel. Scales engraved. In felt lined mahogany hinged box. |
| Area of Use | Topography |
| Comment | Scale set is nearly identical to those on the Tavernier-Gravet Eclimetre. They are attributed to the Frenchman Col. Goulier (c.1783) for use in solving topographic (stadia) surveys. ETS Lejard, 112 Rue De Charenton is stamped in well beneath slide. Lejard (& L'Hermite) were succesors in 1890 to the firm: Richter, Guyard, Canary & Cie. This firm was known since 1780 for their surveying instruments. I know of two other examples in a private collection that are in brass and stamped with the name: 'Lejard & L'Hermite' |
| Rarity | RRR |
| Donor | Collection of Ed Chamberlain |
| Match Number | 206 |
| 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. |