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Unusual 10-inch fish-tail Hewlett with incuse GE marking in center.

Thomas Hewletts are often unmarked.  Marked ones have the following marking: 


Various other letters and numbers may be included which might refer to lot numbers or manufacturing year dates.  I have a Baby Hewlett with the marking, THOMAS HEWLETT-35, and a 7-1/2-inch fish-tail Hewlett with the just marking, PAT SEPT. 15, 14.  Some of the unmarked Hewletts were either not struck with the marking device, slightly struck, or the glaze was so thick it obliterated the marking. 

Unusual 6-inch Hewlett-type with obvious early Thomas glaze.  It was probably a strain insulator.

Locke worked to improve the Hewlett design.  The channel for the U-bolt link had to be drilled out after the clay form was dried.  Locke tried casting the Hewlett forming the interlocking channels as part of the casting process, but this proved unsuccessful.  One of the Locke employees came up with a rather simple solution.  Minor Gouverneur (resident of Victor, NY) was granted a patent on November 29, 1927 (application filed on April 7, 1921) for a way to cut the channel while the clay was still plastic (wet).  He used a design similar to the standard Hewlett except the channel projecting above the top surface (and bottom, too) was tubular (as opposed to dome shaped on the Thomas Hewlett).  In other words, the copper U-bolt link passed through the center of a porcelain body similar to a doughnut (see the patent drawing).  The cut-out channel in the porcelain was very smooth and did not produce unnecessary strain on either the metal parts or the porcelain.  This patent went hand-in-hand with an earlier patent granted to Gouverneur on April 18, 1922 (application filed on May 26, 1920).  The earlier patent claimed the use of a special metal tool to cut the internal channel for the U-bolt link.  This may have greatly simplified the manufacture (cost) of the Hewlett but it was not enough to overcome the important disadvantages of the design.  Both Gouverneur patents were assigned to Locke which was his employer.


Sometime just prior to 1925, Locke designed a new Hewlett which they called the Strap Link Series.  This new insulator used the same basic interlocking design but utilized different coupling hardware that fit in rectangular holes (channels) cut into the porcelain.  They claimed the rectangular holes permitted “the use of flat connecting links and gives a larger bearing surface between the links and porcelain”.  The insulator was shaped like a flying saucer and had a slightly larger diameter of 11”.  I have seen a couple of these fairly scarce insulators with the LOCKE R=¥ insulator logo marking.


New Strap-Link Hewlett shown in the 1925 Locke catalog.

Hewlett was granted another patent on July 8, 1924 (application filed Sept. 14, 1921), for an unusual suspension disk with the same interlocking design.  This insulator had deep flanges formed in the body (see patent drawing) that the patent claimed would help the insulator sustain higher mechanical and electrical stresses.  Similar U-bolt interconnecting hardware was used but with a slightly different coupler.  I’m fairly certain that I have seen one of these insulators but don’t recall who had it.  I would be interested to hear from anyone who has this insulator and would appreciate a good photograph of it.

This story would not be as complete without mention of a patent interference suit.  Louis Steinberger was granted a patent on November 17, 1908, upon his application of January 20, 1908, which claimed an insulator quite similar to the interlocking design claimed in the Hewlett patent application.  Remember the Patent Office had received the Hewlett application on April 20, 1907.  Having discovered the error, the Patent Office declared interference between the two claims on November 2, 1911.  The Appeals Court ruled on October 9, 1913, in favor of Hewlett with an appeal being made to the Supreme Court.  Steinberger wrote to Buck in October 1905 detailing his idea; however, Buck had made sketches of his invention in March or April 1904.  I assume the Supreme Court ruled in favor of Hewlett because his patent was granted on September 15, 1914. 

For those of you who do not know, Louis Steinberger was the owner of Elctrose Mfg. Co.  From about 1900 to about 1929, he obtained dozens of mostly unimportant patents for various uses of his composition insulators.  The composition material used in the Electrose insulators was similar to the early plastic known as Bakelite.  Electrose insulators were copies of many of the popular designs and many forms of insulators were widely advertised.  Literally every design and idea Steinberger conceived was either granted a patent or advertised as being available.  Electrose insulators evidently obtained some continued success with small customers; however, few of the unattractive specimens have found their way into collections.

An 8-inch Hewlett design strain insulator made by Pittsburg and shown in the No. 20 catalog (circa 1920).

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