| Name | Keuffel & Esser N 4102 Surveyor's Duplex |
| Front Scales | D Sin d = Cos l&h C Tan = Tan I Az |
| Back Scales | Vert. 1/2 Sin 2a A = B Ci C = D Vert. 1/2 Sin 2a |
| Type of Rule | |
| Material | Engine divided celluloid laminated mahogany |
| Dimension (mm) | |
| Area of Use | |
| Origin of Rule | Michael O'Leary |
| Match Number | 4405 |
| Comment | |
| Thumbnail | No Picture |