Glass Telephone Insulators

There just might be some glass telephone insulators that have been handed down as heirlooms or nicely displayed in a cabinet of a relative. But did you really know what you are looking at?

With the telephone and poles with their wires across miles of areas for decades, they help provide telephone service. Up until the 1940s, the wires that carried the signals for telephones and telegrams were insulated with chunky pieces of glass. There was also a time when Bakelite and ceramic were used, but this was far less common. inside a glass insulator, there are screw threads and these are to attach the insulator to the telephone pole using a wooden screw. Then, the live wire could run across the grooves in the exterior, directing the wire safely to the next connection point.

They were similar in size to a large paperweight, and these insulators would later become out-of-date by composite insulators which came on the market. You could easily see the glass insulator up on the poles. These glass pieces had a variety of colors. From bell jar blue to olive green to royal purple and deep cobalt, they came in just about any color imaginable.

These glass pieces also came in different shapes. From Mickey Mouse, beehive, signal, and pony, among others. Numbers on the insulators correspond to function. Numbers 10-99 are for battery rest insulators, 100-375 are for American threaded insulators, 376-699 are for non-American insulators, 700-799 are for unthreaded American insulators, and 1000-1199 are for miscellaneous.

It has been quite a while that many people have collected the glass insulators and displayed them in their homes. Placing them on a windowsill allows the sunshine to highlight the color. There have been many glass jar manufacturers who also made insulators, which explains the wide range of colors. Names like Corning, Pyrex, Kerr, and Whitall Tatum will be familiar to collectors of bottle glass.

Check with some relatives and see if they have or did have these wonderful glass insulators.

Photo: A variety of some of the shapes and colors of glass telephone insulators.

Related FamilyTree.com Blogs:

Saying ‘Hello’ on the Telephone

History of the Telephone

Telegrams

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