400 HYDROGRAPHIGAL SURVEYINO [chap, xviii. 



and the operation of letting go and heaving up by hand must 

 be repeated until it is certain that the weights are off, using the 

 screw brake each time for letting go. 



When the weights are gone, screw down the screw brake, 

 and holding the brake lever by hand, run out the regulating 

 screw, disconnect the springs and hook the spring balance, 

 stopping the legs of the springs loosely to the balance to keep 

 them out of the way. 



See the guiding lever in gear. 



Bring to and set up the swifter, which may be ready in position 

 round the grooved wheel, the latter being secured to the shaft 

 by means of the T head screw when required to connect. 



Unship the winch handle, and heave in by the deck engine, 

 taking care not to heave in so fast as to bring a greater strain, 

 as shown by the spring balance, than 100 or 130 pounds. In 

 smooth water and depth less than 2,000 fathoms the strain may 

 be as little as 70 or 80 pounds with the wire coming in at a good 

 pace. 



When the indicator shows 30 fathoms, stop the deck engine, 

 and heave the remainder in by hand. 



When the hemp appears at the surface, heave very slowly, 

 and when up to the machine secure the reel by screwing down 

 the screw brake, and lift the rod in by hand. 



It is very important to guide the wire on to the reel carefully 

 and evenly by the guiding apparatus. Wire badly wound is 

 sure to develop slack turns on running out, and will probably 

 kink and snap. 



When the rod is up disconnect the guiding gear, and get 

 everything ready for another cast. 



During the whole of the operation the ship must be care- 

 fully looked after, in order to keep the wire up and down, or 

 as nearly up and do^vn as possible. 

 Manage- Though perfectly simple to effect after a little practice, 

 Shk) ° inexperienced officers frequently part the wire or get erroneous 

 soundings, and the following notes may be of service until 

 experience is gained. 



Sounding from forward, when there is little or no current, 

 all sails are furled except the spanker, which should be set with 

 the sheet to windward. 



Keep the wind slightly on that bow on which the sounding 



