Bathymetry, the art of measuring depths in the sea, especially for the purpose of investigating the vertical range of distribution of plants and animals. An extensive series of such bathymetric measurements was made by H.M.S. Challenger (1872-76), the deepest made being at 4575 fathoms.
Bathymetry
Chambers's Encyclopaedia, Volume 1: A to Beaufort, p. 796
Source scan(s): p. 0823