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![Figure 41 ship4243.jpg Figure 41](/sites/default/files/styles/max_1300x1300/https/s3.amazonaws.com/s3-east-testmedia-noaa.woc.noaa.gov/dam/Photos/legacy/pl23_ship4243.jpg?itok=kp__KOKj)
Description
Figure 41. Thomson pneumatic sounder, devised by Sir William Thomson, was anextremely simple device designed for use with his sounding machine on a steelline. Although based on the action of pressure on gas or liquids, it also usedthe original concept of using a chemical means to note the depth attained. (Image credit: Oceanographic Museum of Monaco | Y. Berard)