The ebony staff and the four vanes are missing. The sky-end of the staff is pyramid-shaped.

The scales are from 90° to 38° (side one); from 90° to 28° (side two); from 90° to 13° (side three) and from 90° to 6° (side four), this is vice versa (for zenith distance). The maximum reading accuracy is 10 arcminutes for each side.

Hendrik Mooy (1715-65) was a cross-staff maker In de Jonge Lootsman (at the sign of The Young Pilot) in Amsterdam. The business was continued by his widow until her death in 1795. Presumably she continued to sell cross-staffs with her husband’s name, as the only other recorded cross-staff by Hendrik Mooy, in the Maritime Museum Rotterdam (inv. no. M.483), is also dated after his death.

Object Details

ID: ZBA4373
Collection: Astronomical and navigational instruments
Type: Cross-staff
Display location: Not on display
Creator: Mooy, H.
Date made: 1779
Exhibition: Time and Longitude
Credit: National Maritime Museum, Greenwich, London
Measurements: Staff: 746 x 18 x 18 mm; the lengths of the vanes would have been 510 mm (side one); 358 mm (side two); 168 mm (side three); 68 mm (side four).

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