In fig. 3 (col. 683), a a are arms working loosely upon a pin at b, con necting them with the,rod c. The sounding line is attached at d to the bridle connecting the upper ends of the two arms. The conical weight sliding upon the bar, is held in its position during the operation cf sounding by a looped line passing under the base of the cone, and loosely hung on the spurs, e e, of the arms ; immediately on the sound ing-line being relieved of the weight of the apparatus by the latter touching the ground, the arms drop into the position shown by dotted lines, and the loops slip off the spurs, thus detaching the cone altogether, which slips off the her. But here is supposed to be a defect in the apparatus, inasmuch as the force necessary to draw the rod from the aperture of the cone, when in a much inclined position upon rocky bottom, is found enough to break the line at great depths.
Another excellent form of simple apparatus was invented by Mr. Skead, R.N., Master of H.M.S. Tartarus, and found by Captain Spratt to answer admirably in comparatively shallow water. Fig. 4, is a sketch of it. The sounding-line is attached to a small metal hi 1S57, Lieutenant (now Commander) Dayman, R.N., was ordered to check the deep soundings which had been taken by the Arctic ring, which slides in a groove in a bar of quarter-inch iron, and 12 inches in length, having a small hook at one end, and a weight at the other, hollowed and jagged so as to bring up any portion of the bottom. This can be used with either shot or pig-iron, and on reaching the ground the weight a descends and unhooks the sinker, which being left at the bottom the simple apparatus is easily recovered without much strain on the sounding-line. The position of tho hook at the moment of detachment from the weight is shown at f.
The result of Captain Mansell's labours can be best explained by the following section (3).
Europe and North America, preparatory to the laying of the Atlantic electric cable. (TELEGRAPH, SU13MARTNE]. The following (4) is a section published by him, and shows in a remarkably satisfactory manner that the examination of the bed of the ocean at any part of the globe is probably within the power of man even with existing apparatus. In no part of the Atlantic under his observation did he find the depth beyond 2424 fathoms, or about 2i miles.
It is unnecessary to mention more than the leading facts connected with deep sea soundings. It becomes, however, an net of justice to remark that the United States' Oovernmcnt, who took the lead in sounding the Atlantic, arc doing the same in the Pacific. The United States' schooner Fennimoro Cooper was commissioned by Lieutenant Brooke (the experienced officer who invented the sounding apparatus bearing his name) for the purpose.
The only other deep sea soundings which we shall mention are those by Captain Sir F. L. McClintock, of Il.M.S. Bulldog, in the Northern Ocean in 1S60. It has been shown that much of the success of previous experimenters had depended on the instruments in use. One great object also had been to collect as much of the sea bed at each operation of sounding as possible. Up to 1860 very many contrivances had been in use to effect this, with various results. Captain McClintock had been provided with a modified form of Brooke's machine, but it did not answer his expectations. Much attention was given to improve ments by Mr. Roughton, his chief engineer, and Mr. Steil, his assistant ; also by Dr. Wallich, naturalist to the ship ; but Mr. Steil succeeded admirably in contriving a double-scoop machine wherewith to bring up a considerable quantity of the sea bed. It will be henceforward known as the "Bulldog sounding machine," and is of the form shown in col. 684.
In this, Lieutenant Brooke's plan of a hollow sinker is combined with Bunnies claws, but the section of its scoop requires some little explanation. The two parts a a' and b b' move like shears on the pin, c, in fig. A. Another view of them is in fig. 13, in which e e are two studs, which fit the two holes loosely in the cone, as in c at x. When the cone is descending it rests on these two studs and collars, being steadied by the line in A and 13 marked a. A strong india-rubber band, i, is attached, so that on the apparatus reaching the ground, the sounding line, o, being relieved from the weight, allows the claws to fall open, as in 13, and the part of the line a, being released, the cone tilts off the studs, e e, and falls, remaining on the ground ; the part of the line a, unreeving through it, as a in B, and the claws and scoop being secured to the part m, are hauled to the surface ; the removal of the cone from e e allowing the india-rubber bands to compress and close the scoops while in the ground, inclosing about 4 lbs. of the bottom of the sea.
Captain McClintock's results will be best understood by the following sections of his principal soundings.
All the above sectional diagrams are upon the same relative scale, namely, 30 to I, and each is referred to the inch. Much valuable information on deep sea sounding may be obtained from 3Iaury's works on the Physical Geography of the Sea : and many very useful details are recorded in the pages of the Nautical Magazine.' [SEA.]