. Fig. 20. Opening and closing mechanism for large horizontal nets, shown in use. at n: the former is $\ lb. in weight and stream-lined in form, the latter is 22 lb. in weight and apart from the conical extension piece is similar in shape. The smaller messenger travels at a rate of 3^-47 min. and the larger at about 4-5 min. per 1000 m., the speed depending largely on the angle of the warp. The entire apparatus is made of phosphor bronze except for certain pins, at points where exceptional strength is required, which are of steel. Apart from the defects shown in the stop this apparatus proved
. Fig. 20. Opening and closing mechanism for large horizontal nets, shown in use. at n: the former is $\ lb. in weight and stream-lined in form, the latter is 22 lb. in weight and apart from the conical extension piece is similar in shape. The smaller messenger travels at a rate of 3^-47 min. and the larger at about 4-5 min. per 1000 m., the speed depending largely on the angle of the warp. The entire apparatus is made of phosphor bronze except for certain pins, at points where exceptional strength is required, which are of steel. Apart from the defects shown in the stop this apparatus proved all that could be desired, but as is explained further on, the results obtained with these large horizontal nets were not always satisfactory. Depth Gauges. To determine with any accuracy the depth at which mid-water nets are being towed is a matter of some difficulty. In most deep-water investigations the data on this point appear to be based mainly on guess-work, and in a recent expedition all attempts to determine the level are abandoned, and the only information given regarding
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectscientificexpedition
