Archive image from page 307 of The depths of the sea;. The depths of the sea; an account of the general results of the dredging cruises of SS. 'Porcupine' and 'Lightning' during the summers of 1868, 1869 and 1870, under the scientific direction of Dr. Carpenter, J. Gwyn Jeffreys, and Dr. Wyville Thomson depthsofseaaccou02thom Year: 1874 260 THE DEPTHS OF THE SEA. [chap. VI. there ougrht to be one or two tubs about two feet in diameter and twenty inches deep, and eacli tub should be provided with a set of sieves so arranged that the lowest sieve fits freely within the bottom, of the tub,
Archive image from page 307 of The depths of the sea;. The depths of the sea; an account of the general results of the dredging cruises of SS. 'Porcupine' and 'Lightning' during the summers of 1868, 1869 and 1870, under the scientific direction of Dr. Carpenter, J. Gwyn Jeffreys, and Dr. Wyville Thomson depthsofseaaccou02thom Year: 1874 260 THE DEPTHS OF THE SEA. [chap. VI. there ougrht to be one or two tubs about two feet in diameter and twenty inches deep, and eacli tub should be provided with a set of sieves so arranged that the lowest sieve fits freely within the bottom, of the tub, and the three succeeding sieves fit freely within one another (Fig. 52). Each sieve is pro- vided with a pair of iron handles through which the hand can pass easily, and the handles of the largest sieve are made long, so that the whole nest can be lifted without stooj)ing and putting the arms Fig. 52.—Set of DredirinK Sieves. into the water. The upper smallest sieve is usually deeper than the others; it is made of a strong open net of brass wire, the meshes a half inch to a side. The second sieve is a good deal finer, the meshes a quarter inch to a side. The third is finer still, and the fourth so close as only to allow the passage of mud or fine sand. The sieves are put into the tub, and the tub filled up to the middle of the top sieve with sea-water. The top sieve is then half filled with the contents of the dredge, and the set of sieves are gently moved up and down in the
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