The former and present function of the ocean in the history of the earth and in its economy has forged bonds of kinship between oceanography and many other branches of science. Ever since the ocean became the world‐encompassing highway of communication, its surface aspects, embracing the movements of the waters in waves, tides, and currents, have been subjects of observation. With the advance of the physical sciences and a knowledge of the extent of the ocean came the realization that so large an expanse of a substance having the highest known capacity for heat must, to a large extent, govern the external temperature of the earth and exercise an important influence as a factor in geophysics. But centuries of voyaging did not extend marine observations beyond the delineation of coasts and the service of navigation; and, in the middle of the nineteenth century, the sea remained unfathomed, and the observations of the physicist, the chemist, the geologist, and the biologist did not extend beyond the shallow coastal water