Page:The New International Encyclopædia 1st ed. v. 18.djvu/410

SOUND, SOUNDING. 856 SOUSA. taken (using the twine mostly) with fairly accu- rate results,, though, as no specimens of the bot- tom were obtained, they were open to question. In 1853-54 Passed Midshipman J. M. Brooke, U. S. N.. brought out his cup and detachable sinker, which enabled specimens of the bottom to be ob- tained while using a heavy weight to keep the line taut when running out. Brooke also devel- oped his table of 'standard casts' utilizing the time interval and weight of line out, and he much improved the sounding apparatus. The Civil 'ar put an end to the deep-sea work of the United States Navy for many years, but it was carried on most successfully by the British, especially by Captain (afterwards Admiral) F. P. Shorthand, who improved the Brooke sounding machine, and was one of the first, if not the first, to enunciate the important rule in regard to ten- sion on tile line, viz., "A sounding line should not be permitted to run free, but should be resisted by a force equal to the weight in water of a length of the line equal to the depth to be deter- mined." The success of • the Brooke device and its modifications in bringing up specimens of the bottom and its organisms attracted the attention of naturalists and geologists, and their curiosity caused dredging in great depths to be attempted. The results of the early (1867-69) work of Count Pourtales under the direction of the United States Coast Survey brought about renewed interest by showing, as Pourtales says, "that animal life exists at great depths in as great an abundance as in shallow water." In 1872 the British Gov- ernment fitted out the celebrated ChaUenger Ex- pedition (q.v. ) for investigating everything con- nected with the ocean depths. Strange to say, although Sir William Thomson had invented his sounding machine and submitted it to the British Admiralty several months before the Chnllenger was ready, it was rejected for imperfections which might have been easily corrected, and the Challenger sailed with her antiquated outfit of sounding material, whereby a vast amount of time was lost as well as space for supplies and specimens. The United States ship Tuscarora under Captain Belknap sailed from San Francisco only four months after the Challenger, but the United States Navy Department was wise enough to supply her with one or more Tliomson ma- chines in addition to the ordinary rope outfit. The new machines were not entirely satisfactory at the start, but were easily brought into work- ing shape by the Tuscarora's officers, and after very few trials entirely superseded the old ap- paratus. Since that time all deep-sea work has been done by machines, and thousands of sound- ings have been taken to determine the location of the submarine cables which have now become so numerous. The Thomson somiding machine is of two types, deep-sea and coasting. The latter is now used by nearly all large steamers and by many small ones. It consists of an iron-braced wooden frame- work or casing which incloses a steel drum about 18 inches in diameter and three inches thick. The disks forming the sides of the drum project be- yond the circumference, forming a broad deep groove for carrying the wire (.3-stranded galvan- ized wire rope is now generally used). On each side are cranks for winding in. and on one side there is a friction brake and clutch; while on the other there is a dial, showing the number of fathoms (0 to 200) out, which is operated by gearing from the axle of the drum. The sinker consists of a lead of the usual shape, weighing about 22 pounds, through which is thrust an iron rod, the whole sinker being 46 inches long from bottom of lead to top of rod. The wire rope is made fast to a fathom or tw'o of small soft line, which is secured at the other end to an eye in the upper end of the sinker rod. The manner of ob- taining the depth is independent of the length of wire out, and the depth is registered I)y means of a Thomson chemical tube, a Tanner-Blish tube, or the depth recorder. The Thomson tube is a slender glass tube, about two feet long, closed at one end, and filled with chromate of silver. It is placed in a slightly larger brass tube, which has holes in it to admit the sea water freely and is lashed to the sinker. The machine is installed near the stern or on the ship's rail. To sound, the sinker is lowered over the stern, the line dropped in a fair leader to insure free running, and when all is ready the brake is tripped by a movement of the crank. The sinker drops rap- idly to the bottom and the moment it reaches it the line slacks perceptibly and the reel is stopped. The line is then reeled in. It the Thomson tube is used, it is removed from the brass receptacle and laid against a special scale. The sea water has forced itself in the open end to a distance depending upon the pressure (i.e. the depth) ; as far as it reaches the chemical in the tube is discolored, and this point falls abreast the divi- sion of the scale which corresponds to the depth of water. Since the measurement is independent of the amount of wire out. the sounding may be taken with the ship going at full speed if the depth is not too great. The Tanner-Blish is similar to the Thomson tube, except that it con- tains no chemical. If the tubes are kept care- fully dried the distance the water has risen is easily noted; and by redrying the tubes they may be used over and over again. The depth recorder works on a similar principle, and is at- tached to the sinker in the same way. The pressure of the water acts against a piston which compresses a spring and carries a sliding index. When the pressure is slacking the piston returns to its initial position xinder pressure of the spring, but the index remains at the point of the scale to which it is pushed, so that the depth is read off at once. The Thomson sounding machine for great depths is similar to the small one, but has a special form of brake which adjusts the tension in accordance with Captain Shortland's rule, and has of course a much greater length of line. The Sigsbee machine is much used in the United States Navy. It differs from the Thomson chiefly in having an automatic spring governor to ease the strain on the wire due to the motion of the ship: though there are other points of dissimilarity. It is the invention of Captain C. D. Sigsbee. of the United States Nai-y, who has done much deep-sea, depth, and current Avork in the Atlantic and Gulf of Mexico. See Deep- Sea Exploration; Oceanography. SOUSA. sTio'za. John Philip (1854—). An American bandmaster and composer. He was born in Washington. D. C. and was educated there. He held the position of bandmaster of the United States IMarine Corps at Washington from 1880 until 1892, and during that period