| Name | Keuffel & Esser 4090 Original prototype for 4090 Universal rule, dated 1899 |
| Front Scales | A = B C = D DF = C S = A |
| Back Scales | A = BI CI = D DF = CI L T = D |
| Type of Rule | slide rule |
| Material | engine divided hard wood |
| Dimension (mm) | |
| Area of Use | generic |
| Origin of Rule | Bob Otnes |
| Match Number | 4621 |
| Comment | |
| Thumbnail |  |