probably made in London
This 'frictionless' ship's log was the first effective model to be commercially produced, and was originally patented by Edward Massey in 1802. This example is a development known as the 'A1 Harpoon Log' patented in 1861, and was made around 1880, probably by T. Walker & Son Ltd., a scientific instrument maker based in London, but with a factory in Birmingham.
The mechanical log has a five blade propeller, each blade marked with an anchor and 'T.W'. The white enamelled dial plate has three dials and is marked: 'T. WALKER'S/PATENT/HARPOON/SHIP LOG/-A.1.-/London'. As the brass outer case rotates, it moves the hands around the dials, thus ascertaining the speed of a ship as it passes through water.
Thomas Walker (1805-1871) was Edward Massey's nephew. Although he set up in business in Birmingham separately, he became interested in his uncle's invention. He improved it, began making them for Edward Massey's successors, and finally the business was acquired by Thomas Walker & Son.
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