CHAP, xvm.] DEEP-SEA SOUNDINGS 397 



but some officers have successfully accomplished it from aft in Method of 

 bad weather. A projecting platform is fitted on the forecastle, Machine 

 to wliich the machine is bolted so as to plumb the water, being 

 pointed in a direction slightly on the bow. An endless hemp 

 swifter of 2-inch rope connects the deck engine and sounding 

 machine. Tliis is led tlirough blocks to the forecastle, and so 

 to the machine. One or two turns are taken round the drum 

 of the deck engine, and the bight passes through a leading block 

 with a jigger attached, which is placed abaft the deck engine. 

 By means of the jigger the swifter can be kept to the requisite 

 amount of tautness. The details of this arrangement ^nll of 

 course vary in different ships, and mth individual tastes. 

 Specially -made sister-blocks for guiding the swifter are now 

 supplied. 



As the wire runs out, the regulating screw of the brake must 

 be gradually screwed up, so as to increase the power of the 

 brake in proportion to the amount of wire out. The regulating 

 screw is marked for each 500 fathoms. In fairly smooth water 

 the brake will at once act when the weights strike the bottom, 

 and the reel stops. 



When sounding in depths of less than 3,000 fathoms it 

 is best to use only one spring, but beyond that depth two 

 springs are required. The marks on the regulating screw are 

 only intended as a guide ; the real test is that the brake is 

 just on the balance so as to act when the strain lessens, wliich 

 may be known by the s\\d veiling frame being just lifted off the 

 stop. As the wire weighs 7| pounds for each 500 fathoms, the 

 500-fathom mark on the screw should be at the position in 

 which the screw has to be to sustain a weight of 7| pounds ; 

 the 1,000-fathom mark 15 pounds, and so on. This can be 

 tested and the marks verified. 



A spring balance is supplied for attachment to the brake 

 lever when heaving in, by which the amount of strain can be 

 seen, and the deck engine worked accordingly. 



It is necessary to establish some system of signals by which signals 

 the officer on the forecastle, who is carrying out the sounding, 

 can control the helm, main engines, and deck engine, both by 

 day and night. 



The signals given in Figs. 80 and 81 have been used with 

 success for regulating the helm and engines for day work : 



