Insulator Historical Timeline! 1920-1929

Key events are noted by approximate date.  Hyperlinks will provide additional information.  Please feedback additional key dates or note any needed corrections.  Dates considered particularly significant are highlighted in red.

• February 3, 1920:  Robert M. Johnston of Detroit, MI assigned to Jeffery Dewitt patent for a metal spider-like attachment for suspension insulators.  This patent was used for many years by the Jeffery Dewitt company and can frequently be found on their distinct blue glazed suspension insulators.  (US Patent 1,329,770) -- (Additional Patent Image) -- [Full Patent Text]
• April 19, 1921:  Charles Le G. Fortescue and George I. Gilchrest, both of Pennsylvania patent for a multipart insulator design that balances the insulator skirts to the electrical field around the conductor.  This patent was assigned to the Westinghouse Corporation and has been implemented in a number of Westinghouse styles including M-3401, M-3422, M-3520, and M-3811. (US Patent 1,274,998) -- (Additional Patent Image) -- [Full Patent Text]
• 1922:  The McLaughlin Glass Company begins making insulators.  According to William McLaughlin in "Dreams of Glass" they made between 45 and 50 million insulators in nearly 13 years.  Mclaughlin is known to have made 12 styles of insulators.
• March 15, 1927: Scott Cutter patents an enhanced cutter tree insulator. (US Patent 1,620,804) -- [Full Patent Text]
• July 16, 1928:  James H. Brookfield dies - James was the son of William Brookfield and both were involved in the Brookfield Glass Company.
• July 31, 1928:  Leon T. Wilson of East Orange, N.J. patent for carrier circuit telephone insulator with a conductive coating to make the capacitance of the insulator more stable between wet and dry conditions.  The CD 118 with copper skirt is somewhat similar to this idea.  This patent was assigned to the A.T.& T. Co.  Interestingly enough, this patent was applied for the same day as a very similar patent by Chester S. Gordon which was not granted until almost a year later (See US Patent 1,701,562).  (US Patent 1,678,663) -- [Full Patent Text]
• October 23, 1928:  William S. Cook of Parkersburg, West Virginia patent for a multipart porcelain design with a top wore groove sloped to match the wire droop between poles.  The idea was to reduce the stress on the wire as it comes off the wire groove.  (US Patent 1,688,411) -- [Full Patent Text]
• December 11, 1928:  Chester S. Gordon of New York, N.Y. patent for an under cross-arm insulator to increase the protection from moisture for telephone carrier circuits.  No known insulator matches this patent which was assigned to A.T.& T. Co.  (US Patent 1,694,415) -- [Full Patent Text]
• January 22, 1929:  Albert Edward Marshall of Baltimore, MD patent assigned to the Corning Glass Works for the design of a radio strain insulator and glass composition.  This patent was implemented in several Corning designs.  (US Patent 1,700,066) -- [Full Patent Text]
• February 12, 1929:  Chester S. Gordon of New York, N.Y. patent for a carrier circuit telephone insulator with a conductive coating to make the capacitance of the insulator more stable between wet and dry conditions.  It also covered the threading of the inner skirt to provide additional leakage distance in the protected area of the skirt.  This patent was assigned to A.T.& T. Co.  (US Patent 1,701,562) -- [Full Patent Text]
• February 26, 1929:  Rufus Gould of New York, NY patent for a dry spot insulator assigned to the Postal Telegraph Co.  This patent was implemented in Whitall Tatum CD 182 and porcelain styles U-173, U-174, and U-175.  It called for a large inner skirt gap where the drop wire could be potted to keep wetness out.  (US Patent 1,703,853) -- [Full Patent Text]
• April 9, 1929:  Leon T. Wilson of East Orange, NJ assigned to A.T.& T. CO.  patent for a low loss glass insulator design.  This patent was implemented in Whitall Tatum CD 176 and the recently discovered Hemingray version CD-176.5.  (US Patent 1,708,038) -- [Full Patent Text]
• April 16, 1929:  William D. Kyle of Milwaukee, WI patent for a lag screw insulator to mount to buildings and poles as a dead end or wire drop support.  (US Patent 1,709,477) -- [Full Patent Text]
• July, 23, 1929: Scott Cutter patents a strengthened porcelain cutter tree insulator. (US Patent 1,721,657) -- [Full Patent Text]

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