IMPROVE- MENTS IN AND RELATING TO OVERHEAD TELEGRAPH LINES OR OTHER WIRES FOR CARRYING ELECTRIC CURRENTS, AND IN INSULATORS FOR THE SAME
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by Joseph Slater Lewis at the Office of
the Commissioners of Patents on the 31st December 1883.
JOSEPH SLATER LEWIS, of Birkenhead, in the County of Chester. " IMPROVE-
MENTS IN AND RELATING TO OVERHEAD TELEGRAPH LINES OR OTHER WIRES FOR
CARRYING ELECTRIC CURRENTS, AND IN INSULATORS FOR THE SAME."
This invention consists: First. In an improved method of terminating overhead
telegraph wires. Second. In an improved telegraph insulator and mode of
fastening the iron bolt therein. Third. An improved coupling or safety joint for
over head lines.
The form of insulator hitherto used for this purpose has generally been of the
kind known as Bright's shackle, but this description is open to very serious
objection on account of the insulating surface being so very small. Terminal
insulators are also used with strong wrought-iron bolts with large collars; but the
side strain upon these is so great that it is impossible to keep the wires properly
regulated. This system is also objectionable in consequence of the liability of the
cross arm splitting, or in consequence of the strain being too great for the bolt.
These defects I have overcome by cementing in an insulator of special construction
a long iron bolt with a welded collar upon it, at about that point where the line
wire is looped round the top of the insulator; I attach a wrought or other metal
bracket to the side of the cross arm and a similar bracket to the cross arm
immediately below; I then slip a cast-iron sleeve over the long iron bolt which
has at its lower end a large flange, to fit upon the flat surface of the bracket before
mentioned. The bolt is now inserted, first through the top bracket and then
through the bottom one, and is made somewhat thinner from a little below where
it rests in the top bracket, and is threaded for a few inches upon the thicker
portion; a nut is slipped up the thinner portion of the bolt and engaging with the
before mentioned threads upon the thicker part: the bracket, sleeve, and insulator
are brought home to almost one solid piece. The lower end of the bolt is affixed
by nuts or otherwise to the lower bracket. By the use of this insulator the danger
of the ironwork giving way is avoided, and no matter how high the tension of the
line wire, I consider it to be impossible, in consequence of the leverage which the
bolt has over the insulator, for it to be drawn out of its vertical position. In some
instances I dispense with the brackets mentioned and insert the bolt through the
ordinary holes in the cross arms instead, forming the bottom end of the sleeve with

page_text: a kind of saddle, which when tightly screwed from underneath, as already described,
prevents the wood work from splitting.
The insulator can be fastened to its bolt by forming a cylindrical or parallel
socket in the centre of the insulator, at the upper end of which I form a female
screw of about half the internal diameter of said socket. The insulator bolt has
upon its upper end a male screw of several inches in length, and some distance
below this I weld a collar. I now take a length of thick twine of a soft nature or
other material, and I wind the same round the bolt until it has covered half of said
male screw.
I then slip a washer over the end of the bolt and insert the whole in
the socket before described. The screw on the bolt now engages with the screw
in the socket and forces the washer down until the cavity is firmly jammed and
the bolt rigidly fixed. The twine may or may not be dipped in hot paraffin, wax,
pitch or other preservative. This prevents the liability of the bolt to split the
insulator which is very often the case with the present kind in consequence of the
unyielding nature of the cement employed in fixing them together, or in
consequence of no allowance being made for expansion and contraction both
longitudinally and laterally.
In the line wire, and near one of the insulating supports, I insert a short length
of wire lightly thinner than the line wire. I then take a length of the latter and
form a spiral round, but some distance from the thinner section. The two ends of
the spiral I attach to the main wire on either side of the thin piece. The thin
piece not being able to bear such a heavy strain as the other part of the wire is the
place where all breakages caused by over straining or corrosion will naturally occur.
On it breaking, the spiral allows the tension of the line to fall to a moderately low
one, and yet notwithstanding this electrical communication is not interrupted, and
the joint can be repaired or the wire renewed at will.