II. HYDROGRAPHY. 613 



3009. Bulldog Clam, for bringing up specimens of the sea 

 bottom; date 1860. Used in H.M. ships "Bulldog" and "Por- 

 cupine," North Atlantic Ocean. 



The claw is kept open by a tubular sinker weight, resting on the four 

 horns. When the weight is detached on reaching sea bottom, the india- 

 rubber bands contract, closing the claw, and thus securing the sea bottom 

 contained within it. 



3010. Fitzgerald Sounding Machine, combining appa- 

 ratus for detaching the weight and procuring specimens of the sea 

 bottom; date 1867. By Lieutenant Fitzgerald, R.N., employed 

 in H.M.S. " Cordelia," in deep sea sounding between Jamaica 

 and Cuba. 



An iron sinker weight (represented by wood model) is hooked to the side 

 of the sounding bar, and the hook or lever, to which the sounding line is 

 attached, is inserted in the hole at the upper end of the bar. When suspended, 

 the weight of the sinker keeps the lever in the hole and the bar nearly 

 vertical. On reaching sea bottom, the scoop is driven into the ground, and 

 the hook being freed by the slackening of the sounding line the weight falls 

 over ; the action of hauling in the sounding line reverses the bar, unhooks 

 the weight, and the scoop closes with its contents. 



3011. Hydra Weight Detaching Apparatus ; date 1868. 

 By Gibbs, artificer, H.M.S. " Hydra." Used in sounding 

 Atlantic and Indian Oceans. 



The wooden models represent (exact size) iron sinkers, each of one hundred- 

 weight ; they are suspended on the sounding tube by the iron ring and wire, 

 to a button which protrudes through a steel spring on the sliding rod above, 

 the spring being kept back by the weight of the sinkers. On reaching sea 

 bottom and the sounding line slackening, the rod slides down, the sinker 

 weights then resting, the steel spring throws the suspending wire off, and the 

 weights are left behind as the tube is drawn through them. A butterfly valve 

 within the tube at the bottom secures a portion of the sea bottom. 



3012. Baillie Weight Detaching Apparatus; date 1872. 

 By Navigating Lieut. C. W. Baillie, R.N. In general use in 

 H.M.S. "Challenger." 



Iron sinkers of half a hundredweight each (exhibited in wood models) in 

 numbers sufficient for varying ocean depths, are placed on the sounding tube 

 and suspended by the ring and wire to two shoulders that project from the 

 sides of a sliding rod working in the upper part of the sounding tube. On 

 touching sea bottom and the sounding line slackening, the sinker weights 

 draw the sliding rod downwards, and the shoulders passing within the sounding 

 tube, the wire is thrown off, and the weights released. The lower portion of 

 the tube, to which a valve is attached, receives the specimen of the sea bottom. 



3013. Burt's Bag and Nipper, for sounding in moderate 

 depths without stopping the ship's way. Invented by Mr. Gould, 

 an American (about 1812). 



The bag is first soaked in water to render it air-tight, and when used is in- 

 flated ; a wooden tube and peg is affixed for the purpose. The sounding line 

 is placed in the nipper or snatch attached to the bag, and on the sounding lead 



