Report of the Commissioner of Fisheries to the Secretary of Commerce and Labor for the fiscal year ended .. . length is inserted in theeyes at the side of the castings. The rod is raised as far as it will goand is automatically locked in position by the rack and pawl. Theinstrument is then lowered until it rests on the bottom and the rod isreleased by pulling on a line attached to an eye at the upper end ofthe weight. As the plunger always falls through the same distance,it strikes the bottom with a uniform impact, and the depth of itspenetration is a comparative measure of the consistency of
Report of the Commissioner of Fisheries to the Secretary of Commerce and Labor for the fiscal year ended .. . length is inserted in theeyes at the side of the castings. The rod is raised as far as it will goand is automatically locked in position by the rack and pawl. Theinstrument is then lowered until it rests on the bottom and the rod isreleased by pulling on a line attached to an eye at the upper end ofthe weight. As the plunger always falls through the same distance,it strikes the bottom with a uniform impact, and the depth of itspenetration is a comparative measure of the consistency of thebottom. In practice, the instrument is used from an anchored boat, and tosecure a representative reading from 6 to 10 tests are made closetogether. Any markedly aberrant readings are eliminated, on theassumption that the plunger has either come into contact with anaccidental obstruction, such as a shell, or has fallen into a crabholeor other minor cavity. The average of the remaining depths ofpenetration, read off in inches in a scale stamped on the rod, is 10 OYSTER BOTTOMS OF MISSISSIPPI SOUND, Mud soundlug machine used to determine character of oyster bottom. OYSTER BOTTOMS OF MISSISSIPFI SOUND, ALA. ] 1 regarded as the index of the bottom consistency. The followingarbitrary scale is adopted in this report. Hard bottom Penetration less than 4 inches. Stiff Penetration between 4 and 8 inches. Soft Penetration between 8 and 13 inches. Very soft Penetration between 13 and 18 inches. Ooze Penetration over 18 inches. On the accompanying chart the consistency of the bottom is indi-cated by symbols which are more readily read than lettering—ablack circle indicating hard bottom; a black semicircle, stiff mud; ablack quadrant, soft mud; a circle containing two crossing diameters,very soft mud; and a circle with one diameter, ooze. Bottom fallingwithin the first two classes, provided it be not shifting sand, is firmenough for oyster planting; the harder the bottom the more
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Keywords: ., bookcentury1900, bookdecade1900, bookpublis, booksubjectfisheries
