To all whom it may concern:

Be it known that I, HENRY PRENZEL, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Supporting Insulators for Telegraph-Wires; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to supporting insulators for telegraph, telephone, and other electric wires; and the improvement consists in making the insulator in two separable parts, both of which are provided with a central screw-threaded opening, through which is inserted the screw-threaded supporting-peg, the wires being securely held between the upper and lower parts of the insulator, as will be hereinafter shown and described.

In the accompanying drawings, Figure 1 shows an elevation of my improved insulator fitted in position and having two wires passing through and securely therein.  Fig. 2 is a cross-section of Fig. 1.  Fig. 3 is a plan. Fig. 4 is a cross section showing a modification of Fig. 1.  In this figure the top part of the insulator is made convex and the under or bottom part concave.  Fig. 5 is a cross-section showing another modified form in which the top is concave and the bottom part convex.

A represents the cross-piece attached to the telegraph-pole.

B is the peg or support to which the insulator is secured.

C is the lower half of the insulator, which is made of glass or any other suitable material.  C' is the upper half of the insulator. Both of these parts are provided with a central screw-threaded opening fitting over or upon a corresponding screw-thread formed on the supporting-peg B.

c c are grooves on the upper surface of the lower part of the insulator.

d d are telegraph-wires fitting into the grooves c c.

C2 is a square projection formed on the top of the upper half, C', for the purpose of fitting a wrench thereto, so that the two parts may be tightly screwed together.  C" is a similar square projection on the base of the lower half C, for a like purpose.

The under surface of the upper

half and upper surface of the lower half of the insulator may be made flat as shown in Figs. 1 and 3, or they may be formed, respectively, with convex and concave surfaces fitting into each other, as shown in Figs. 4 and 5, in which case the grooves c c are made to conform to the shape of the surface of the lower half of the insulator.  By this latter means a more secure grip is obtained upon the wire, as the two parts coming together form a circular bend upon the wire corresponding in shape to the grooves.

The lower part, C, of the insulator being fitted to the supporting-peg B, to secure the wire or wires in position, it is only necessary to fit them into the grooves c c, draw them to the required tension, and screw the upper half, C', down toward the lower half, C.  As the wires project beyond the grooves c c, they are held firmly between the two parts of the insulator.

It will be readily seen that by the use of an insulator constructed in this way the wires can be easily and quickly adjusted, and at the same time accomplish a saving of the wire ordinarily used in tying the telegraph-line to the insulator.

I am aware that telegraph insulators have been made in two separable parts connected together by a screw passing through a smooth central opening in each of said parts and screwing into the wooden bracket or the stem holding the insulator, also that insulators have been made with the upper separable part provided with a screw-threaded opening fitting on the supporting peg.  I do not, therefore, claim either of these inventions.

What I do claim, and desire to secure by Letters Patent of the United States, is--

In a supporting-insulator for electric wires, the lower half, C, having an internally screw threaded opening, and provided with a groove or grooves, c, in combination with the upper half, C', having an internally screw threaded opening, and the screw threaded supporting peg B, all substantially as and for the purpose described.

In testimony whereof I affix my signature in presence of two witnesses.

    HENRY PRENZEL.

Witnesses:

THOMAS D. MOWLDS,

OTIS EGAN.