To all whom it may concern:

Be it known that I, FREDERICK HENRY WITHYCOMBE, of the city of Montreal, Province of Quebec, Canada, have invented certain new and useful Improvements in Insulators; and I do hereby declare that the following is a full, clear, and exact description of the same.

It is well known that the glass and other insulators used on telegraph and other electric lines are frequently made the targets of and are damaged by stones and other missiles. The damage resulting partially or wholly destroys their usefulness and necessitates the trouble and expense of replacing them, besides causing inconvenience by the interruption of communication.

My invention relates to the special construction or formation of the exposed surface of the insulators apart from the general design or material employed.

My invention has for its object to render insulators less liable to breakage by providing a simple and efficient means to enable them the better to withstand the impact of foreign bodies.

The invention consists generally in replacing the smooth outer surfaces of insulators as now made of glass, porcelain, or other insulating material by an outer surface construction of small protuberances, ridges, or depressions, each protuberance or ridge being of greater height the thickness. These small protuberances, ridges, or intervening portions between the depressions, which may be of any desired section, form an exterior construction which will crush or break down readily with the impact of missiles.  This breaking down of the projecting or intercepting parts cushions the blow and relieves the main portion or body of the insulator or extension therefrom from the full severity of the impact.  It will thus be seen that the small parts with which the missile first comes into contact offering a sufficiently less resistance than that portion of the main body or extension therefrom it is intended to protect will crush or crumble under the force of impact, and thus cushion the blow by using up a large proportion of the energy.  My experiments have proved this to be the case.

Insulators having a number of petticoats, whether extending horizontally, vertically, or obliquely, of proportions which render them very easy of breakage by missiles can this be made to offer greater resistance to fracture by forming the exposed surfaces in the way and as herein described.

Reference is made to the annexed drawing, which is an elevation, half in section, illustrating one application of the invention to one form of insulator.

The insulator shown is of the same general form as those now in use, having a central cylindrical part

1 surmounted by a dome-shaped upper portion or crown 2 and having depending from it the petticoat 3.  The interior is provided with the usual threads 4, adapted to screw on the end of the supporting pin, peg, or stick.  The usual groove 5 is provided for attaching the wire.

The insulator shown in the drawing is provided with horizontal ridges or projections 6, each of greater height than thickness, and depressions 7, encircling the exposed surfaces of the insulator, the projections being of such small thickness or cross-section as to allow of a large number being formed, so as to effectively protect every portion of the exposed surface of the insulator and at the same time be easily broken or crushed by the impact of a stone or missile.  To provide for the flow of moisture, from the insulator, vertical or oblique channels a are provided at intervals. The function of such a surface formation (made up as it is of a large number of ridges of small cross-section, which may be of any desired form) is that when a missile strikes the insulator it will first come in contact with such ridges, which being of a fragile or easily, broken and yielding formation will give way to the impact of the foreign body.  Thus in the form shown the projecting ridges will be first broken down and the energy of the impact largely expended in crushing these parts. The result will be to cushion the blow and reduce its severity as regards the main body of the insulator or extension therefrom, and unless the impact be very severe and violent the insulator will be saved from fracture.

Having described my invention and the way in which it is to be applied, what I claim as new, and desire to secure by Letters Patent, is--

1. An insulator the entire outer or exposed surface of which is in the form of a protective cushion or guard made up of small projecting portions or ridges or intervening portions between depressions of small cross-section so as to be structurally more fragile than the main body or any extension therefrom on which they project in uniform depth and proximity, and having downward leading channels for the flow of moisture, substantially as shown and described.

2. An insulator the entire outer or exposed surface of which is in the form of a protective cushion or guard made up of small and easily-broken horizontal ridges and having water-channels, substantially as shown and described.

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

FREDERICK HENRY WITHYCOMBE.

Witnesses:

FRED. J. SEARS,

LORNE A. MACKENZIE.