Page:Popular Science Monthly Volume 78.djvu/255

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and the bottom. One consisted of a heavily weighted ten-foot iron ring to which was lashed a lined bag of fine mesh. This net was wrecked in a typhoon encountered off the coast of northern Luzon, as it stood lashed to the fore rigging, and was replaced by a net of Norwegian model. The bag of the latter was made with a shear board at each corner of its triangular mouth, set so as to draw the net down as it was towed, and at the same time to hold the mouth open for thirty feet on a side.

These dredges and tow nets are put over the starboard side of the ship by a heavy boom swung from the foremast. The steel dredging cable, five or six thousand fathoms of which are wound on a huge drum on the berth-deck below, passes over a sheave at the heel of this boom so geared as to indicate upon a dial the number of fathoms of cable paid out. To relieve the severe tension on the dredging cable, which often amounts to four or five tons, two sets of rubber buffers are inserted in the rigging of the boom. One of these, fastened perpendicularly to the foremast, moves a pointer over a scale, indicating roughly in tons the strain upon the cable. Fisherman's luck prevails on the Albatross, as elsewhere, and often the dredge is brought to the surface with a great hole torn in the side; or occasionally the whole bag gives way under a big load as the dredge is being lifted aboard, and the collector sees all his expected treasures float rapidly astern or disappear into the dark blue water beneath the ship.

PSM V78 D255 Sounding instruments.png
A Set of Sounding Instruments. 1, water bottle; 2, thirty-five pound shot; 3, Thompson ball-cutting sounding rod; 4, bottom specimen cup; 5, sixty pound shot; 6, deep-sea thermometer. (Photograph by DeLong.)