Miner Robinson's patented porcelain bushing or tube

A New High-Insulation Porcelain Bushing.

Many electricians have experienced the annoyance of having the ordinary form of porcelain bushing drop out of place from the lack of proper wedging. To overcome this difficulty a new style of bushing has recently been patented by Mr. Miner Robinson, 302 Equitable Building, Boston, Mass., and is to be used in leading wires through beams and other materials. The improved tube is provided with three narrow ridges running longitudinally, which serve as a wedge to hold it firmly in position. The device may be driven in completely or only part way, the latter being very advantageous when the wires turn corners. The prominent features claimed are a high insulation resistance, low cost of manufacture and security in fastening.

Porcelain Bushing.