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Deep-Sea Exploration

that branch of thalassography which investigates the depths of oceans, seas or lakes, determines the nature and distribution of the organic life there to be found, the temperature, constitution and specific gravity of the water at varying distances from the surface, the causes and characteristics of ocean currents, the geological changes in the way of gradual or rapid upheaval or subsidence caused by volcanic action and the formation of atolls and other islands.

Measurements by means of a weighted line were used by the earliest navigators.

It is said that in the Middle Ages depths of 8,000 meters were attained, but the accuracy of such soundings must be questioned. Sir John Ross in 1818 brought up a considerable amount of icecold slime from a depth of 978 fathoms. On the strength of these measurements it was believed that the greatest depth of the ocean was to be reckoned as about 1,000 fathoms; but shortly after, Capt.

DEEP-SEA EXPLORATION Sir James Clark Ross, during a voyage to the South Seas claimed to have found between Brazil and St. Helena, on June 3, 1843, a depth of more that 4,- 800 fathoms. In 1847 Captain Stanley, of the British Navy, reported soundings at 15,000 feet between the coasts of Africa and South America.

Copper wire was used instead of rope for soundings as early as 1838, but it proved to be too weak. In 1854 J. M.

Brooke, of the United States Navy, invented a detaching apparatus which worked a revolution in deep-sea operations. Since then systematic attempts have been made with improved sounding apparatus and especially in connection with the laying of cables to discover the exact lay of the submarine bottom.

After the "Challenger" expedition of 1872-1876, two systems of apparatus were invented, one by W. E. Hoyle, assistant editor of the "Challenger" reports; the other by the Prince of Monaco. The latter machine goes down closed. It opens automatically at the bottom by means of a spring shutter and is again closed by a "messenger" before it begins its ascent. No previous ship had been so well equipped for natural history research as the "Challenger" which added thousands of new specimens to zoölogy.

About the same time with the "Challenger," the German ship "Gazelle," under Baron von Schleinitz, and the United States steamship "Tuscarora" accomplished a great deal toward the exploration of the deep-sea. Other expeditions were made between 1878 and 1882 by the ship "Faraday," and by the warship "Gettysburg" in 1876, by the "Alaska" in 1878, by the "Essex" in 1877-1878, by the "Saratoga" in 1879, and by the "Wachusett" in 1879. Still more important results were obtained by the scientific men in charge of the three cruises of the United States Coast and Geodetic Survey steamer "Blake" in the Gulf of Mexico, in the Caribbean Sea, and along the Atlantic coast of the United States in 1877-1880.

Besides these specific explorations the South Atlantic Ocean was explored by the steamship "Seine" in 1889. In the Indian Ocean the United States warships "Enterprise" and "Essex" in 1886 made explorations. The English ship "Egeria" in 1887-1889, made extensive measurements of the S. W. part of the Indian Ocean.

In August, 1899, the United States ship "Albatross" left San Francisco fully equipped with a staff of scientists, for the purpose of deep-sea exploration, examination of coral reefs, etc., in DEER Oceanica. The first sounding was made near the Marquesas at a depth of 1,955 fathoms. It seemed to prove that this group of islands rises from a plateau 2,000 fathoms deep and 50 miles wide.

Numerous soundings were taken in the North Pacific by vessels of the United States Navy in 1900 for the purpose of developing feasible cable routes between the Hawaiian and Philippine Islands.

A sounding of 5,269 fathoms, about 70 miles to the S. E. of Guam Island by the "Nero," in 1899, was taken in a locality near where the "Challenger" in 1875 took its greatest sounding (4,475 fathoms). This was surpassed by the German survey ship "Planet" in 1913, which made a sounding of 5,348 fathoms 4 miles E. of the north of Mindanao.

The best sounding-rod (as these devices are termed) of to-day is doubtless the Brooke devise as modified by Admiral Sigsbee. Sigsbee's modification may be described as follows: the sinker is an 8-inch cannon-shot weighing 60 pounds. A hole runs through it large enough to admit the sounding rod. Upon the shot are cast two ears, like the ears on a pail, to which a wire bail, like a pail-handle, is attached. The soundingline is fastened to the ring shown near the top of the cuts. The sounding-rod is a brass tube about one-eighth of an inch thick, quite sharp on the lower edge. It operates thus: The shot is placed upon the sounding-rod. As long as the weight of the shot is borne by the sounding-line the hook will sustain the shot. But the moment that strain is relieved by the shot striking the bottom the hook doubles under and releases the wire handle of the shot. At the same time the weight of the shot buries the sharp lower edge of the sounding-rod in the bottom. This forces up a valve and a portion of the bottom enters. At the first movement toward reeling in the line the shot slips off the sounding-rod and remains behind, and the valve at the bottom of the sounding-rod closes, imprisoning a sample of the bottom. This device has been tried many hundreds of times in great depths, and it has rarely failed to detach the shot as well as bring up a liberal sample of the bottom.