Figure 36. Ericsson pneumatic sounder, invented in 1835 by John Ericsson of USS
MONITOR fame. This was among the first instruments to use the principle of
pressure needed to compress air a given amount to derive the depth of water.
Image ID: ship4238, Voyage To Inner Space - Exploring the Seas With NOAA Collect Photographer: Y. Berard Credit: Oceanographic Museum of Monaco