[Newspaper]
Publication: Weekly Rocky Mountain News
Denver, CO, United States
vol. 40, p. 6, col. 7
CRUSHED GRANITE INSULATORS.
Crushed granite insulators for electric light purposes may take the place of the glass insulator now in use. Crushed granite is a late invention of a New York man, who has not yet secured a patent upon it. The granite is crushed in a retort with about 3,600 degrees of heat. It is then subjected to an enormous hydraulic pressure and formed into the shape desired. Its particular advantage is that it will stand 200,000 volts, while 1,500 volts will split an ordinary glass insulator. The patentee of the crushed granite means to use it for insulators in underground street railway construction and also for decorative purposes.
