100 Years Of History
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1994 National Display
| 1850's | The exact date of the start of production of insulators is unknown. Some advertising mentions producing "Telegraph Glasses and lighting rod insulators." |
| 1871 | (December 19) Robert Hemingray receives a patent for the molding of telegraph insulators. |
| 1870's | The earliest embossed insulators produced by Hemingray are embossed "PATENT DEC.19.1871". Over a dozen styles are produced, the most common being CD 132, 133, and 133.4. |
| 1883 | (November 13) Samuel Oakman patents the Double Petticoat insulator. This design feature is incorporated in a number of styles of insulators, including some styles produced by Hemingray. |
| 1884 | (February 12) Samuel Oakman patents the CD 145 "Beehive" style insulator. This style becomes the Western Union Standard Double Petticoat insulator. Again, several insulator companies, including Hemingray, begin producing this style in large quantities for telegraph use. |
| 1880's | During the 1880's the embossing "H.G.CO." replaces the "PATENT DEC.19.1871" embossing and several new styles of insulators are introduced. Most of these are the new double petticoat styles CD 145, CD 151, CD 162 and CD 164. |
| 1893 | (May 2) Ralph Hemingray receives a patent for drip points or "teats". This feature is quickly added to nearly all styles of insulators that are in production. |
| 1890's | The embossing "HEMINGRAY" appears on several new styles of insulators. The earliest of these probably are the No 8 CD 112.4 and the No 9 CD 106. Also "HEMINGRAY" replaces the "H.G.CO." embossing on most existing styles. |
| 1899 | The "Provo" style CD 283 is patented and developed for high voltage power transmission and is used on a 40 KV transmission line of the Telluride Power Transmission Company in Provo, Utah. |
| 1910 | CD 152 is developed as a new standard for telegraph work. |
| 1919 | "MADE IN U.S.A" first appears on Hemingray insulators per an international agreement to mark any items for export with the country of origin. |
| 1922 | CD 154 is developed as a replacement for CD 152 for telegraph work. |
| 1931 | At the demand of Western Electric Company, Hemingray switches to "clear" glass. The color is not actually crystal clear but ice blue. |
| 1933 | Owens-Illinois buys the Hemingray Glass Company. Production remains at the Muncie, Indiana plant. |
| 1936 | Hemingray produces true clear insulators. A true clear glass is needed for the production of glass building blocks, and this glass is used for insulator production also. |
| 1937 | The one billionth Hemingray glass insulator is produced! |
| 1940's | During the war years, several styles are designed to use less glass. This is the start of CD 163 and CD 165 production, and the "slim" CD 113. |
| 1952 | The Kimble Glass Company takes over the Hemingray insulator division and produces several new power insulator styles embossed "KIMBLE". |
| 1966 | The Hemingray plant is shut down and insulator production ceases. |
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Last updated Sunday, August 27, 1995