An all brass harpoon ship's log designed by Thomas Walker, England, circa 1863. A ship log is an instrument used for the calculations of a ship's speed. The A1 model is similar to the 1861 pattern for a harpoon type ship's log designed by Walker, but with the addition of a float plate. The wheel-work of this type of log is enclosed in a cylindrical case of the same diameter as the body of the rotator or fan, and the latter was brought close up to the register. Each fin is stamped T. W. with an anchor motif. The entire body of this log spins. The porcelain dials are protected by a turn of the surrounding housing and states "T. WALKER'S PATENT HARPOON SHIP LOG A1, LONDON. Also, the name "AMY CRAIG" is etched on to the float plate, possibly the name of the vessel where she was used. Made in the United Kingdom. Comes in it's original dovetailed wood storage box. A great maritime item for the serious collector. The ship log measures 19 inches long exclusive of the line. The wood box measures 24 inches X 6 X 6 1/2 inches.