EQUIPMENT. 9 



which pass over the pulleys J, J (Figs. 4, 5). The tubes are 

 hinged at K, K (Figs. 4, 5), so that the upper sections may be 

 lowered for convenient stowage. They are graduated for the 

 number of pounds pull on the wire, the upper arm of the cross- 

 head being the index. The cross-head H, containing the pulley 

 L (Fig. 4), moves on the guides M, M (Fig. 5), which are 

 screwed to the tubes. The pulley L is rigidly attached to its 

 axle by a key. To the axle is attached an odometer, iV"(Fig. 5). 

 The pulley is exactly one yard (half -fathom) in circumference 

 on the face, less the allowance for thickness of wire. One 

 half the number of revolutions shown by the odometer will 

 therefore give the number of fathoms of wire payed out or 

 reeled in. 



The object of the swivel pulley, S (Figs. 4, 5), is to allow 

 for tlie reeling in of the wire while the vessel is steaming 

 ahead. 



The scales W, X (Fig. 4), should be of the kind that have a 

 long movement of the pointer for a slight extension of the 

 springs in the scales. In paying out the wire the difference 

 between the readings of the scales X and W will be the num- 

 ber of pounds of resistance applied to the reel by the friction- 

 rope. The wire to be used is the same as that recommended 

 by Sir William Thomson, namely, steel piano-forte wire, No. 

 22, Birmingham gauge, weighing fourteen and a half pounds 

 to the nautical mile. The friction-line should be a quarter of 

 an inch or slightly less in diameter, and should be oiled or 

 kept wet with water where it comes in contact with the fric- 

 tion-score of the reel. The weight is attached to a stray line, 

 to prevent kinking when it reaches the bottom. In taking a 

 sounding with the machine, allow the reel at first to revolve 

 slowly until assured that everything is working well, then ease 

 up the friction-line and follow out as nearly as practicable the 

 rule governing the amount of resistance to be applied to the 

 reel, which should be, as is stated by Thomson, always more 

 than enough to balance the weight of wire out. It is impossible 

 to say how fast the wire may be allowed to pay out, since the 

 limit of safety varies with circumstances, and depends on the 

 state of the sea and the extent and rapidity of the ship's rolling 

 and pitching motions. 



