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 77, containing the pulley 
L (Fig. 4), moves on the guides M, M (Fig. 5), which are 
screwed to the tubes. The pulley Z is rigidly attached to its 
axle by a key. To the axle is attached an odometer, JV (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 the 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-seore 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 pitehing motions. 
