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![Figure 48 ship4505.jpg Figure 48](/sites/default/files/styles/max_1300x1300/https/s3.amazonaws.com/s3-east-testmedia-noaa.woc.noaa.gov/dam/Photos/legacy/pl23_ship4505.jpg?itok=sZ_QImVx)
Description
Figure 48. Walker log, used to measure the speed of a ship under way. Thisinstrument was towed behind a vessel and the number of turns of the rotor during a given interval was directly proportional to the speed of the vessel throughthe water. This instrument was apparently invented prior to 1882 and sold under the name T. Walker's patent harpoon ship log. (Image credit: Oceanographic Museum of Monaco | Y. Berard)