1/13/2024 0 Comments Signal isolator glass![]() 40, Hemingray-42, Hemingray-45 (or Armstrong DP-1), and (the oldest insulators on this pole) aqua “beehives” which are marked “H.G.CO.” Most glass insulators have been dismantled in recent years, but these were still in the air when I took this photo on September 14, 2017! Some of the insulators here include Hemingray No. Telegraph pole with glass insulators along a railroad in Indiana. The oldest glass insulators date from about 1846. The material, glass, is itself an insulator (not a “conductor” or “transformer” as insulators are often incorrectly labeled in antique malls and flea markets).īoth glass and porcelain insulators have been used since the early days of the telegraph, but glass insulators were generally less expensive than porcelain, and were normally used for lower-voltage applications. Insulators were necessary by serving as a medium for attaching the wires to the poles, but much more importantly, they were required to help prevent electric current loss during transmission. ![]() ![]() The telephone was invented by Alexander Graham Bell in 1876.Īs time went on, networks of “open wire” telegraph lines, and later, telephone lines, were developed and built throughout the country, and these lines required the installation of insulators. The electric telegraph (in the United States) was developed by Samuel Morse in 1837, and the first message was sent by Morse in 1838. Long before the modern era of computers, cellphones, smartphones, fiber-optic cables and the internet, long distance electric/electronic communication consisted primarily of the telegraph and telephone. ![]()
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