Harpoon towing Log A2 – T. Walker, Birmingham, 19th century
From the 17th century onwards people had made many attempts to devise a mechanical log which would automatically record the ships distance done. Edward Massey invented a mechanical log in 1802 with four blades which was used by the Admiralty from 1807-1815. As the rotator was dragged behind the ship then the log rotated and the revolutions were transformed in miles on the dials, to be read after the rotator was brought on deck. The design of Massey was further refined by Thomas Walker and Son, including the stabilizer. Walker took out a patent for the A1 Harpoon Log in 1861.
This A2 log came after the A1. It doesn’t have a stabilizer. Rotary slide twists to reveal three dials on porcelain face. The first registers the miles up to 100, the second registers the units up to 10 mile, the third registers quarters of a mile. The four rotor blades are stamped with anchor motif and initials T.W.
The production commenced in 1863 and ceased in 1919. Mainly used in steam powered high speed vessels such as used by the Royal Navy.
Details and design features suggest manufacture date around 1880.
Date: ca. 1880
L: 50 cm (19.7 in)
Signed: T. WALKER’S Patent HARPOON SHIP LOG A.2. London.
Condition: perfect with signs of use