| Date | 1925 |
| Maker | W. Watson & Sons |
| Place | London |
| Material | Aluminium |
| Inventory no. | 58805 |
Alidade
| Appearance | Tip | Sights | Pinholes | Notches | Description |
|---|---|---|---|---|---|
| Double-ended, original. | Flat | None | None | None | The sights have broken off and are in the box with the astrolabe. |