Glass Telegraph Insulators

Insulators are those glass or porcelain things you see on the tops and crossarms of telephone poles. Their purpose is to insulate the electrical wires they carry, so that electricity (for telegraph signals) don't all leak into the pole and into the earth. 

They were originally designed to keep the wires linking telegraphs and telephones insulated from the wooden poles that held them aloft. The Hemingray Glass Company was an American glass manufacturing company. Robert Hemingray and Ralph Gray founded the company in Cincinnati in 1848. In its early years the company went through numerous and frequent name changes, including Gray & Hemingray; Gray, Hemingray & Bros.; Gray, Hemingray & Brother; Hemingray Bros. & Company and R. Hemingray & Company before incorporating into the Hemingray Glass Company, Inc in 1870.

The Hemingray company had factories in Cincinnati and Covington, Kentucky with main production in Muncie, Indiana. Though Hemingray was best known for its telegraph insulators, the company produced many other glass items including bottles, fruit jars, pressed glass dishes, tumblers, battery jars, fishbowls, lantern globes, and oil lamps. In 1933, Owens-Illinois Glass Company purchased the company but retained the production facility in Muncie under the Hemingray name.

This is an insulator found in our museum.