Insulator Historical Timeline!
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.
- October 24, 1861: The Transcontinental
Telegraph, which connected St. Joseph, Missouri and Sacramento, was
completed by the Western Union Telegraph Co. and its associates. (Also
see 1869 below).
- November 30, 1863: Ralph Gray died, leaving Robert Hemingray
as the administrator of his will. Click
here for more details.
- 1864: James Brookfield hired to operate the Bushwick Glass Works in
- November 29, 1864: David Brooks of Philadelphia, PA patent
for a metal and glass ramshorn insulator. (US
Patent 45,221) -- [Full Patent Text]
- April 4, 1865: S.F. Van Choate of New York, NY patent for an unusual
ramshorn insulator and mounting bracket design. (US
Patent 47,141) -- [Full Patent Text]
- July 25, 1865: This important
patent was by Louis Cauvet for the a method of forming internal threads an
insulators to allow them to screw onto a threaded pin. Previous
insulators were threadless and held on the pin by friction. Brookfield was the first to license this patent.
(US Patent 48,906) -- [Full
- July 27, 1866: Another trans-Atlantic cable was laid with
minimum problems. The length of this cable was about 1680 miles.
The initial rates to use that cable were about $1.00 a letter! This
was a large sum in the mid 1800's. The success of this cable halted
efforts on the Collins Overland Telegraph line which was attempting to
connect North America with Europe with a land line up through Alaska, a
short cable across the Bering Straight into Russia where a 7000 mile
overland line would connect with Europe! Much great threadless glass
was used on the completed portion of this line including Chester and
Tillotson hats. There are rumors that a cache of these insulators may
have been abandoned in Russia for the European end of the line!
- March 26, 1867: David Brooks of Philadelphia, PA patent for a metal
encased rams horn style insulator. (US
Patent 63,206) -- [Full Patent Text].
- May 14, 1867: George Floyd of Cincinnati, OH patent for a
threadless locking pintype insulator. This attribute was implemented
on on an early Hemingray style of CD 732.2, three of which were found in
association with a lightning rod set-up in Cincinnato, OH. (US
Patent 64,654) -- [Full Patent Text]
- June 25, 1867: Darius Stebbins of Wallingford, CT patent for
a lightning rod insulator design. (US
Patent 66,054) -- [Full Patent Text]
- August 6, 1867: Reissue of David Brooks 1864 ramshorn
insulator patent. Many of the Brooks Ramshorns are marked with this
patent date. (US Patent Reissue 2,717)
- October 8, 1867: David Brooks of Philadelphia, PA patent for a
metal and glass ramshorn insulator. (US
Patent 69,622) -- [Full Patent Text]
- October 22, 1867: John L. Waite of Burlington, Iowa patent
for a metal and insulating material ramshorn insulator design. (US
Patent 70,052) -- [Full Patent Text]
- October 22, 1867: Daniel W. Teller and William Savage patent for a
two piece glass block style insulator. I am not aware of any specimens
matching this patent being found. (US Patent
70,132) -- [Full Patent Text]
- November 12, 1867: Thomas J. Lockhart and Josiah Locke of
Pittsburg, PA patent for a lightning rod insulator bracket. (US
Patent 70,727) -- [Full Patent Text]
- November 26, 1867: Merritt L. Wood of Ithaca, NY patent for a cast iron
telegraph insulator. (US Patent 71,564) --
[Full Patent Text]
- December 17, 1867: Homer
Brooke made molds lettered TILLOTSON & other items for Tillotson &
Co -- Follow this link for additional Homer
- March 24, 1868: Cromwell Varley of New York, N.Y. (Citizen of Great
Britain) patent for an improvement in insulator pin preparation. (US
Patent 75,815) -- [Full Patent Text]
- July 1868: Robert
Hemingray successfully constructed and operated a glass press to form
threads in glass insulators.
(Statement to Commissioner of Patents reported in Official Gazette
of the U. S. Patent Office, 22 July 1873).
The style of the insulator first manufactured by this process would
have been un-embossed variants of CD 127.4 or CD 131.4.
Manufacture of un-embossed threaded insulators continued until the
Dec 19, 1871 Patent was awarded and the molds were modified to include the
patent date (most likely early in January, 1872).
- 1869: James Brookfield purchases the
Bushwick Glass Works. It is not exactly known when the name changed to
the Brookfield Glass Co.
- 1869: The Transcontinental
Telegraph, which connected St. Joseph, Missouri and Sacramento, and completed by the Western Union Telegraph
Co was rerouted to follow the Transcontinental Rail Road.
- October 26, 1869: Charles Bush of New London, CT patent for a
rubber liner for a threadless pin to improve the insulating value. (US
Patent 96,198) -- [Full Patent Text]
- November 30, 1869: Alfred G. Safford of St. Albans, VT patent for an
insulator with a cap to protect from moisture. (US
Patent 97,318) -- [Full Patent Text]
to the main timeline page