This insulator was used on phone wires. Insulators were originally designed to keep the wires linking telegraphs and telephones insulated from the wooden poles that held them aloft. Prior to 1925, Australia relied solely on insulators imported from other countries. Glass insulators were first manufactured in Australia in c. 1926 by Australian Glass Manufacturers. Their factory was, and still is, located on South Dowling Road in Sydney. Australian Glass Manufacturers (A.G.M.) had developed a toughened type of glass very similar to Pyrex glass. Since the Pyrex name could not be used due to trademark infringements, they called their glass AGEE for Australian Glass. Many fruit jars, insulators, pie dishes and other glass items were manufactured with this AGEE trademark during the 1926 to 1940 period.Glass insulators are rapidly becoming a thing of the past in Australia with open-wire communication lines rarely existing near metropolitan areas. The remaining open wire lines are being abandoned and dismantled everywhere with very few insulators being saved as interest in them in Australia is quite limited. (ref Australian Insulators web-site). This item is an example of a piece of equipment which has been superceded.A glass telegraph line insulator of double umbrella shape. Glass is coloured purple - AGEE 30 Insulator. It is a tapered cone of thick glass. The inside top is threaded for screwing onto the metal piece on a wooden cross bar.Embossed on outside of bell: "AGEE 30"insulator-glass agee a.g.m. communications telegraphy