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 in. The design of Massey was further refined by Thomas Walker and Son, who took out a patent for the A1 Harpoon Log in 1861. Heath & Co., instrumentmakers in London from 1845-1910, made only a few harpoonlogs (see enamel plate No 1, limited edition) based on Walkers patent of 1861, also with a stabilizer.
On the log there are three dials, the first registers dozens of miles up to 100, the second registers the units up to 10 mile, the third registyers quarters of a mile.
There is a little tolerance on the propulsion with the blades.
With original rope.

Catalog: NM.1-20
Date: 1860 – 1880
LD: 49,5x14cm (19,5×5,6”)
Signed: HEATH & Co, LONDON
Number: 1197
Origin: England
Condition: good and complete