Crighton's Patent for Self-Tying Insulator

CREIGHTON'S [sic] CRIGHTON'S IMPROVED INSULATOR.

THE object of this insulator is to effect the securing of the line wire to the porcelain cup without the employment of binding wire. The method by which this end is effected is as follows: — The wire w is placed in a groove in the top of the insulator, and then an ebonite piece a is added, and finally a porcelain cap c is screwed over the head of the insulator; this presses down the ebonite firmly on the wire and jambs it tight in the groove. In order to effect this object more thoroughly, the lower part of the groove is curved, as shown, so that the line wire only bears on a small surface, whilst the piece of ebonite being slightly hollowed on its under surface has a tendency, when firmly pressed down by the cup, to slightly bend the wire over the curved portion of the groove, and thereby to give the wire a tighter grip. In addition to the care with which the wire can be thus secured, this method possesses advantages as regards insulating properties, for the wire being only in contact at a few points with the porcelain has practically a greatly diminished amount of leakage as compared with wires secured by wire bound completely round the insulator.