To all whom it may concern:

Be it known that I, SAMUEL OAKMAN, of Melrose, in the county of Middlesex and State of Massachusetts, have invented certain new and useful Improvements in Telegraph-Insulators, of which the following is a specification.

My invention relates to that class of glass insulators which are supported upon screw-pegs, and has for its object to so construct the interior of the insulator that it shall have a broad interior band of weather-protected surface for insulation between the exterior of the insulator and the supporting-peg; also, in providing the interior of the insulator with an annular recess for the reception of paraffine or some similar moisture repellent. These objects I attain by the mechanism illustrated in the accompanying drawings, in which -

Figure 1 is an elevation of one of my insulators, and Fig. 2 is a cross-vertical section of the same.

In the drawings, A B C represent the body of the insulator. This insulator has a screw thread, D, formed on its interior, as shown in Fig. 2, of the ordinary style and dimensions of the standard insulators now in general use. I also form on the interior surface an annular recess, C', which serves to receive a coating or body of paraffine or other moisture repellent. Immediately below the recess C' I form the annular shield E and the upwardly projecting recess H.

By the above-described construction I attain, in connection with the internal screw, D, an interior insulating-surface, 1 2 3 4 5 6, Fig. 2, a part of which - viz., the part 2 3 - is especially adapted to receive and retain paraffine. Another part - viz.,the part 3 4 - is doubly protected from the weather; and a third part, 4 5 6. adds to the interior insulating-surface.

The arrangement of the interior of a screw insulator, as above described, gives a great advantage over the ones now in use. By it I am enabled to obtain in a single moderate sized insulator all of the advantages of the different styles heretofore in use.

Having thus described my invention, what I desire to secure by Letters Patent is -

1. A glass insulator having formed within j its interior a screw-thread. D, recess C', shield E, and recess H, all substantially as described, and for the purpose set forth.

2. A glass insulator, having formed within its interior a screw-thread, D, shield E; and recess H, in combination with the screw-peg P, all substantially as described, and for the purpose set forth.

SAMUEL OAKMAN.

Witnesses:

FRANK G. PARKER,

WILLIAM EDSON.