+
-
Backstaff
The backstaff is made from a lignum vitae frame, boxwood arcs, brass rivets, and a boxwood sight vane. There is an inlaid boxwood plate in the main strut. Decorative stars and fleurs-de-lis are stamped at the ends of the arcs.
The transversal scale on the thirty degree arc is from 0° to 25° by 5 arcminutes, and reads to 1 arcminute along the fiducial edge of the sight vane. The graduation on the sixty degree arc is from 0° to 65° by 1°, and on the outer edge has a scale for correcting for the Sun’s semi-diameter.
A replacement sight and shadow vanes have been added.
The transversal scale on the thirty degree arc is from 0° to 25° by 5 arcminutes, and reads to 1 arcminute along the fiducial edge of the sight vane. The graduation on the sixty degree arc is from 0° to 65° by 1°, and on the outer edge has a scale for correcting for the Sun’s semi-diameter.
A replacement sight and shadow vanes have been added.
For more information about using images from our Collection, please contact RMG Images.
Object Details
| ID: | NAV0031 |
|---|---|
| Collection: | Astronomical and navigational instruments |
| Type: | Backstaff |
| Display location: | Not on display |
| Creator: | Patrick, John |
| Date made: | circa 1720 |
| Credit: | National Maritime Museum, Greenwich, London |
| Measurements: | Overall: 635 mm; 20 mm x 635 mm x 360 mm |
| Parts: | Backstaff |