Telephone and telegraph cables are made of any required gauge of wire
and with from 1 to 150 conductors in a cable. In jointing these the
splices are never soldered, the conductors being joined either with a
twist joint or with the so-called Western Union splice. Each splice is
covered with a cotton or silk sleeve or a wrapping of tape, the latter
being preferable, although considerably increasing the time necessary
for making the joint. Great care must be taken that no ends of wire are
left sticking up, for they will surely work their way through the tape
and grounds, and crosses will be the result. The wires should always be
joined layer to layer and each splice very tightly taped in order to get
as much insulating compound around each splice as possible in the
limited space. The splices should be "broken" as much as possible, so as
to avoid having adjoining splices coming over each other. After the
joint has been saturated with insulating compound the wires should have
an outside wrapping of tape to keep them in shape, and then the sleeve
is wiped on and filled. If the insulation resistance of the jointed
telegraph or telephone cable is a quarter of what the cable tested in
the factory, it may be considered that an exceptionally good piece of
work has been done. I have spoken more particularly of fibrous lead
covered cables, as the handling of them includes practically every step
of the work on any other kind of underground cable. In insulating dry
core paper cables a paper sleeve is slipped over the splice, and in
rubber cables the splice is wrapped with rubber tape; all other details
are the same for these as for the fibrous cable.

In the laying of light and power cables every joint, as made, should be
tested for insulation with a Thomson galvanometer, as the insulation
must necessarily be very high, and if one joint or section of cable is
any weaker than another it may be very important in the future to know
it. All tests must be made after the joint has cooled, for while hot its
insulation resistance will be very low.

Tests for copper resistance should also be made to determine if the
splices are electrically perfect; an imperfect splice may cause
considerable trouble. In telegraph and telephone cables the conductors
should be of very soft copper, for in stripping the conductor of
insulation it is very easy to nick the wire, and if of hard drawn copper
open wires will be the result.

All work should be freque