Publication: The McGraw Electrical Directory
New York, NY, United States
JOHNS-MANVILLE HIGH POTENTIAL STRAIN INSULATORS. All parts under strain are insulated with Sheet Mica Discs that will not crush or give out. The entire construction of these insulators is quite simple, and insures great strength and thorough efficiency on the line, regardless of conditions. The insulating surface measures approximately 10 ˝ inches from eye to eye. These insulators are built to withstand a working pressure of 5,000 volts and higher voltages; breaking strain, 8,000 lbs.; diameter, 44 inches.
—H. W. JOHNS-MANVILLE COMPANY. NEW YORK.
KNOWLES INSULATORS. Glass insulators for telephone, electric light and direct current feeder circuits, also standard wiring knobs and tubes. Standard wood cross-arms and pins, standard brackets, Murdock reversible cleats, Murdock porcelain cable insulators, wire specialties, wood and porcelain strain insulators, standard porcelain tubes, etc., are carried in stock. Among other specialties handled are Osgood insulators, Henrion carbon, and G. & G. lamp hangers, various types of porcelain receptacles and malleable iron cleats.
—C. S. KNOWLES, BOSTON, MASS.
LAVA INSULATING STONE is not a volcanic product. It is the mineral steatite which is machined in green condition to any conceivable form and then kilned like porcelain. Superior to porcelain or any known insulation material in its ability to withstand heat and temperature changes. Lava is strong, hard and cheap—worked in immense variety with remarkable accuracy and uniformity.
—AMERICAN LAVA MFG. COMPANY, CHATTANOOGA, TENN.
PORCELAIN INSULATORS. The Mechanical & Electrical Mfg. Company, Chicago, Ill., manufactures a line of porcelain bushings for metal and wood, together with all kinds of electric porcelain, high-tension porcelain foi busbar chambers, insulators, etc., together with standard electric porcelain dies and tools for same.
DUNTON TREE INSULATORS are so constructed that they allow for the sway of tree when the wire is tied in solid to glass insulator. It is constructed so that any single, double or triple petti coated glass insulator that fits a standard pin can be used. It can be attached to any size limb over three-quarters inch in diameter. Two sizes are made, Size No. 1 is especially adapted for all wire up to and including 0000. Size No. 2 for railroad work, capable of ca.Tying any size wire up to and including one million circular mils.
—DUNTON & FIELD, CAMBRIDGE, MASS.