| Name and Model Number | Keuffel and Esser 1744B Wm. Cox Patent 1891 |
| Country of Origin | USA |
| Date of Manufacture | 1897 |
| Front Scales | With Slide 1: A [ B C ] D, With Slide 2: A [ BI CI ] D |
| Back Scales | With Slide 1: A [ B C ] D, With Slide 2: A [ S L T ] D |
| Scale Length | 25 cm |
| Type of Rule | Slide Rule |
| Construction | Celluloid on mahogany, engine divided scales, brass chisel cursor |
| Area of Use | Generic |
| Comment | Brass chisel cursor. Brass end plates wrap around ends of rule.
Front lower stator is inscribed: Wm. COX PAT. OCT. 6, 1891. Back lower stator is inscribed: KEUFFEL & ESSER Co., NEW-YORK. |
| Rarity | RRRR |
| Donor | Collection of Mike Frey |
| Match Number | 269 |
| 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. |