| Name | Keuffel & Esser 1744 B Duplex with interchangeable slides both arithmetical and trigonometrical, dated 1895 |
| Front Scales | A = B C = D second slide: = B C = |
| Back Scales | A = BI CI = D second slide: = S L T = |
| Type of Rule | |
| Material | |
| Dimension (mm) | |
| Area of Use | |
| Origin of Rule | Michael O'Leary |
| Match Number | 4021 |
| Comment | |
| Thumbnail | No Picture |