"Sigsbee Sounding Machine – invented by Charles Dwight Sigsbee and modified from Thomson Sounding Machine. Basic design of ocean sounding instruments stayed the same for the next 50 years. Here the sounding machine is used to set a Pillsbury current meter at a known depth. In: The Gulf Stream, by John Elliott Pillsbury, 1891. Note caption on photo: ""Sounding Machine And Current Meter In Place, Steamer Blake"""
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