March ist, 18S7.] 



SCIENTIFIC NEWS. 



to the base-plate, either first passing through a second 

 pulley at the base of the pillars, or not, as the case may be. 

 The object of rigging the brake-line in this manner is to 

 obtain automatically a varying brake-power which will be 

 in unison with the greater or less strain on the wire. 

 Before explaining how this end is attained, it will be neces- 

 sary to describe another part of the machine. The pulley 

 (C) is mounted in a frame, as may be seen by the perspec- 

 tive view. This frame is arranged to slide up and down 

 between the pillars, suitable guides being provided for the 

 purpose. The pillars themselves are hollow, and each one 



contains a long spiral spring, which is fastened at its lower 

 end to the bottom of the pillar. In connection with these 

 springs a light line is rove in the following manner. It is 

 attached to the top end of one spring, passes up and over a 

 pulley on the top of the corresponding pillar, then down- 

 wards and through a small pulley on the top of the main 

 pulley frame, then back over a second pulley on the top of 

 the other column, and is finally made fast to the second 

 spiral spring inside that column. It will be seen that this 

 cord will serve to hold the sliding pulley frame in its highest 

 position, i.e., at the top of its range of motion, and the length 

 of the cord is adjusted as to give this position when the 

 springs are not extended. Before commencing to pay out. 



the friction cord is hauled down, so as to put a very appre- 

 ciable brake power on the reel. 



By connecting the description of the arrangement of brake 

 line and that of the spiral springs, it will be seen that an addi- 

 tional strain on the sounding wire, caused by the vessel rolling 

 from the sinker, will pull the pulley C and its sliding frame 

 downwards. The movement will vary as the strain, being 

 controlled by the spiral springs in the pillars. The downward 

 movement of the pulley frame will have the effect of slack- 

 ing ihe brake cord, which is rove through a pulley on the 

 frame's under part. The friction on the wheel being thus 

 reduced, the wire will pay out faster, and any undue strain 

 will be avoided. When the ship turns to roll towards 

 the sinker, the strain on the wire is reduced, and if this is 

 continued far enough, the wire will become slack, and the 

 fatal kink will be made. This, however, is obviated by an 

 opposite train of events to those just described. Reduction 

 of strain on the wire will allow the spiral springs, by their 

 reaction, to draw the pulley-frame upwards, and this will 

 tighten the brake cord, so that the wire will pay out very 

 slowly. It is, however, when the sinker strikes the bottom 

 of the cean that the chief function of the friction cord comes 

 into play. When this occurs a great part of the strain is 

 at once taken off the wire, and were there no brake the 

 reel would continue to fly round by its acquired momentum, 

 and the wire would become so slack that there would be a 

 number of turns at once formed. When, however, the 

 weight is supported by the ground, the spiral springs are 

 relieved from strain, and by their reaction carry the pulley- 

 frame up so that the brake is at once applied, in the manner 

 already described, and the reel is brought almost immed- 

 iately to rest, only a short length of the stray line lying 

 loosely on the bottom. The extreme end of the wire, 

 where it joins the stray line, is weighted just enough to 

 keep the wire out of turns when the whole apparatus is 

 at rest. These weights are not sufficient to overcome the 

 resistance of the friction line. It will be seen, therefore, 

 that the spiral springs and the friction line act as an accu- 

 mulator to equalise the strain, and as a governor to prevent 

 undesirable speed of unwinding. 



The number of fathoms of wire paid out is shown by 

 means of a counter placed either on the reel or on the pulley C. 

 In the former case allowance has to be made for riding turns. 

 The beautiful device of Sir William Thomson's, by which a 

 given depthofwateris registered through the varying pressure 

 at different depths compressing air, may of course be used 

 with this apparatus, but in taking deep soundings the vessel 

 is stopped, and there is so little friction from passing under- 

 currents, ordinarily met with, that the wire approaches a 

 vertical line sufficiently for all practical purposes. 



In our illustration on this page a detachable sinker, E, is 

 shown. This is automatically released by a trigger arrange- 

 ment, and left at the bottom, the brass sounding rod which 

 passes through it being alone recovered. It is found cheaper 

 to throw away the iron sinker, rather than expend the time 

 required in the slower winding necessary when recovering 

 it; that is unless sounding in comparatively shallow waters, 

 when a lead sinker is used. 



The bottom having been reached, the operation of wind- 

 ing in commences. A gut belt is put on the fly wheel of 

 the small engine, shown at the rear of the machine in the 

 outline drawing, and passes round a score provided for it 

 on the periphery of the reel. The friction cord is cast off, 

 and the winding-in progresses, the accumulator springs in 

 the pillars, preventing sudden jerks from the move- 

 ment of the vessel. The pulley marked H is for keeping 

 the belt at tension to prevent slipping. For this purpose it 

 is mounted on a sleeve, which slides on the standard, and 

 is pressed down by the spiral spring, as shown. 



