straps and brass buckles.

_Lead Weights._--These weigh 40 lb. each, and the diver wears one on
his back, another on his chest. These weights and the heavy boots
ensure the diver's equilibrium when under water.

_Belt and Knife and Small Tools._--Every diver wears a heavy
waist-belt in which he carries a strong knife in metal case, and
sometimes other small tools.

_Air Pipe._--The diver's air pipe is of a flexible, non-collapsible
description, being made of alternate layers of strong canvas and
vulcanized india-rubber, with steel or hard drawn metal wire embedded.
At the ends are fitted gun-metal couplings, for connecting the pipe
with the diver's pump and helmet.

_Signal Line._--The diver's signal line (sometimes called life line)
consists of a length of reverse laid Manila rope. In cases where the
telephone apparatus is not used, the diver gives his signals by means
of a series of pulls on the signal line in accordance with a
prearranged code.

[Illustration: FIG. 4.--Diver's Telephone Communication with the
Surface.

Q, Battery, with switch and bell in case.
R, Attendant's receiver and transmitter.]

_Telephonic Apparatus._--Without doubt one of the most useful adjuncts
to the modern diving apparatus is the loud-sounding telephone (fig.
4), introduced by Siebe, Gorman & Co., which enables the diver to
communicate viva voce with his attendant, and vice versa. In the
British navy the type of submarine telephonic apparatus used is the
Graham-Davis system. This is made on two plans, (1) a single set of
instruments, for communication between one diver and his attendant
direct, (2) an intercommunication set which is used where two divers
are employed. With this type the attendant can speak to No. 1 or No. 2
diver separately, or with both at the same time, and vice versa; and
No. 1 can be put in communication with No. 2 whilst they are under
water, the attendant at the surface being able to hear what the men
are saying. The advantages of such a system are obvious. It is more
particularly useful where two divers are working one either side of a
ship, or where the divers may be engaged upon the same piece of work,
but out of sight of one another, or out of touch. It would prove its
utility in a marked degree in cases where a diver got into
difficulties; a second diver sent down to his assistance could receive
and give verbal direction