The telegraph manual: a complete history and description of the semaphoric, electric and magnetic telegraphs of Europe, Asia, Africa, and America, ancient and modern.

598 SUBTERRANEAN TELEGRAPHS.
seen, have been filed so as to lap over each other, and yet form
but the thickness of the wire. After the ends are thus placed
together, a very small copper wire is then wound around the
place of splice, as seen by fig. 14. When thus prepared, with
a spirit lamp the solder can be spread upon the joint uniting
the small with the larger wire. If the solder is not carefully
spread on the splice the wires may separate as seen by fig. 15.
which ought never to be the case. After the wires are well
united, the gutta percha is put on and completes the insulation
by uniting it as represented by the dotted lines in fig. 14. This
process is as follows:
Have in readiness a few strips about three eighths inch broad
of very thin gutta-percha sheet, also a little warm gutta-percha about one eighth inch thick, one or two hot tools, and a
spirit lamp.
Remove the gutta-percha covering from along the wire no
further than may be necessary for making the joint in the wire.
Having joined the wire, warm gently with the spirit lamp the
bare wire and joint and the gutta-percha near to it; taper the
gutta-percha over the bare wire until the ends meet; warm
this and immediately apply one of the strips of thin sheet in
a spiral direction over it. Press this covering well on until
cool, then, with the spirit lamp, carefully warm the surface and
proceed as before to put on a second strip of the thin sheet,
observing to wrap it in a direction reverse from the first strip,
always making the commencement and termination of these
coverings to overwrap the previous ones. It is safer to perform
this operation a third time.
Next take a piece of the warm one eighth inch sheet and
cover over the coats of thin sheet, again overwrapping the
original covering of gutta-percha, which should be heated so
as to insure perfect adhesion. Press it well on as it cools, and
when cold, or nearly so, finish off the joints with a warm tool,
working well together the old and new material at each end.
Lastly, and in general, avoid moisture, grease or dirt, and
be careful not to burn the gutta-percha, which would prevent
proper adhesion.
I have been quite particular in these explanations in regard
to the mending of wires insulated with gutta-percha. Some
of the lines, however, in England use wires wrapped with cotton thread, and well coated with a mixture of tar, resin, and
grease. This coating forms a perfect insulator, in the opinion
of some telegraphers. But some ten years ago I employed this
composition to saturate osnaburg coverings to submarine wires,
and I did not find it to answer.