Identifier: deepseasoundingd00usco (find matches)
Title: Deep-sea sounding and dredging; a description and discussion of the method and appliances used on board the Coast and Geodetic Survey Steamer, "Blake."
Year: 1880 (1880s)
Authors: U.S. Coast and Geodetic Survey Sigsbee, Charles D. (Charles Dwight), 1845-1923
Subjects: Blake (Ship) Deep-sea sounding Dredges
Publisher: Washington, Gov't Print. Off.
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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etched, as whenattached to the roping of a seine. The meshes are measured either by thediagonal or by the length of one side. Thus a mesh having each of itsfour sides one inch in length is called a two-inch mesh or one-inch squaremesh. The latter term seems to be the plainer. Professor Agassiz recomfnends changes in the above as follows, and thesechanges have been introduced-into the tables of dimensions already give^i: For main bag of trawl, web to hang fifteen feet instead of twenty feet. For tra^ and jacket of trawl, fifteen-thread cotton instead of nine-threadcotton. The difference in cost and weight is as fifteen to nine. TUBS AND SIEVES. The Blakes supply of these appliances was very simple: a nest ofsieves, from coarse to fine, and several tubs. The tubs were of thick wood,ironbound, and fitted with iron handles. They were about• twenty-fourinches high, twenty inches in diameter at the top, and somewhat less atthe bottom. We found that these answered our purpose well for deep
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> WGO DREDGING AND TRAWLING—APPARATCTS AND METHODS. 155 work, but in the work of the Fish Commission down only to a depth of twohundred fathoms, the hauls being more frequent and the specimens gen-erally less fragile, the special appliances shown in the appendix to thischapter are used with success. STEEL-WmE DREDGE-ROPE. Our rope was made at Trenton, N. J., by the John A. Roeblings SonsCompany. It was one and one-eighth inches in circumference, and wascomposed of six strands laid around a tarred hemp heart. Each of thesix strands was composed of seven galvanized steel wires of No. 19 Ameri-can gauge (No. 20 Birmingham gauge). The ultimate strength of the ropewas 8,750 pounds,* weight per fathom 1.14 pounds in air, and approxi-mately one pound in sea-water; price, eight cents per foot. For the first dredging cruise it was supplied in 3,000-fathom lengths,each length wound upon a separate wooden reel. For the second cruise,the working reel already having 2,700 fathoms upon it, I h

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