Mechanical Depth Finder by Thomas Walker & Son, Ltd--SOLD
The instrument is designed simply to go straight down and find the depth of the bottom. It has an impeller which drives a threaded gear that turns a disk printed from 0-30 fathoms. There would be a sounding lead attached and thrown overboard. As the device makes its way to the bottom, the gear is counting. On the backside there is a flap which drops down and locks the rotor when the device has hit bottom and is raised back to the surface to record the depth. A small plaque reads Walker's "Harpoon" Depth Finder, Thomas Walker & Son Ltd, 58 Oxford St, Birmingham with serial number 1341-M. There is also a special manufacturer's stamp of an anchor and the letters T and W. Circa 1920. New old stock.
Case 11 x 5 x 5 inch. The device is 9 1/2 inch.