To all whom it may concern:

Be it known that we, BRADLEY FISKE and SAMUEL D. MOTT, both citizens of the United States, and residents of the city, county, and State of New York, have invented certain improvements in electrical Insulators, of which the following is a specification.

Our invention relates to that class of insulators for electric-circuit wires wherein the amount of contact of wire with the insulator is decreased by causing the encircling wire to rest on narrow supporting ribs or beads on the insulator-body.  In all insulators of this general character heretofore constructed, so far as we are aware, ribs or beads for bearing up the wire have been formed on the exterior surface of the insulator-body and made to project therefrom.   As such insulators are usually made from glass or ceramic material, Which is quite fragile, these projecting ribs ate liable to be broken off in packing and handling as Well as after the wire has been put up. The wire, also,  is somewhat exposed where is stands off from the body between the ribs.  Otherwise the insulating advantages due to this construction are measurably attained.

In our invention we seek to avoid the liability to injury of the supporting ribs by forming them below the level of the general surface of the insulator-body, as will be hereinafter described.

In the drawings, which serve to illustrate our invention, Figure 1 is a side elevation of our improved insulator as adapted to telephone wires, the securing screw passing through the axis of the insulator.  Fig. 2 is a transverse section of the same on line 22 in Fig. 1.  Figs. 3 and 4 are sectional views, similar to Fig. 2, illustrating modified forms of the supporting ribs.

We can best explain the construction of our insulator by describing how one may be formed of any suitable material.  Take a cylindrical or substantially cylindrical piece of the material

and cut a circumferential groove around the same to receive the wire.  Then hollow out the maternal at intervals across said groove, so as to leave a number of ribs or supports for the wire to rest on, the hollows or cavities being between the ribs.  Thus in the drawings, A is the insulator-body.  a a are the supporting-ribs, provided with recesses in their edges to receive the wire; and b b are the hollows between said ribs, which are bridged over by the wire when in position.  Thus it will be seen that the whole of the supporting-rib is within the margin of the body of the insulator, or, in other words, below its surface.  There are no projecting points to break off, and the wire, when in place, is, in a sense, under cover and protected by the outer surface of the insulator-body, which projects beyond it.  This construction also protects, to some extent, against water during rainy weather.

Figs. 3 and 4 show modified forms of the ribs and will explain themselves.  The precise form of the rib is not material, so long as it serves to support the wire.

Our insulator may be employed for all the purposes to which electrical insulators for wires are usually adapted, and it may be attached in any of the well-known ways.

Having thus described our invention, we claim ---

An insulator for electrical conductors, consisting of a body, A, provided with hollows or cavities b and supporting-ribs a to receive the wires, said ribs being below or within the general level of the exterior surface of the insulator-body, substantially as and for the purposes set forth.

BRADLEY A. FISKE.

S. D. MOTT.

Witnesses:

C. DICKERSON,

ROBT. MACOY.