THE
POPULAR SCIENCE
MONTHLY.
JULY, 1873.
| HOW THE SEA-DEPTHS ARE EXPLORED. |
ONE of the most recent and impressive examples of the interaction of science and art by which knowledge is extended, and man's control over Nature increased, is furnished by the late remarkable investigations into the depths and life of the sea. The taking of soundings is, of course, as old as navigation, and is an indispensable portion of the mariner's art. The record of these soundings was embodied in charts by which sailors were guided in unknown waters. As commerce extended, such observations became more full, and resulted in systematic coast-surveys in which the depth of water, currents, magnetic conditions, temperatures, tides, and winds, were taken into account, and the knowledge thus accumulated gave rise at length to a great science—the Physical Geography of the Sea. About twenty-five years ago a new step was taken toward the extension of our knowledge of sea-depths. Science had given to the world the electric telegraph, and commerce demanded that it should be laid across the ocean. For this purpose the bed of the North Atlantic required to be carefully examined and mapped, and the configuration of the sea-bottom and the nature of its material determined. This gave a new impulse to the art of sea-sounding. The transatlantic cable was laid, got broken, and the end of it was then fished up from a depth of nearly two miles. A great victory was thus gained; the bottom of the sea was no longer inaccessible, and the possibility of its scientific exploration became established. Hitherto, sea observations had main reference to the advantages of navigation and commerce; but, from this time forward, the idea was entertained of pursuing the investigation in the interest of science alone. At the instance of the Royal Society, the British Admiralty, in 1868, granted a small government vessel, the gunboat Lightning, to Dr. William B. Carpenter and Prof. Wyville Thomson, to be used for dredging the bottom of the sea, and investigating its animal life. So promising were the results of
