Insulators are made out of green glass, and used for telephones. One has a broken bottom. Brand name "Hemingray". Used for electrical insulation of telegraphs, controlling electrical current due to their high resistivity.
Insulators are made out of green glass, and used for telephones. One has a broken bottom. Brand name "Hemingray". Used for electrical insulation of telegraphs, controlling electrical current due to their high resistivity.
