The time is July 3, 1873.

The place; the U.S. Patent Office.

The patent of Louis Cauvet has now been around for nearly eight years. Most telegraph companies now see the advantage of using threaded insulators and are probably ordering them for new construction or for upgrading existing lines. Any glass company that is involved with Insulator manufacture is trying to produce threaded insulators. We will be hearing a decision from the Commissioner of Patents about other insulator threading patents. This is actually an appeal to an earlier decision by the Board of Examiner-In-Chief. 

Before the hearing, first some history. If there is a patent application pending in the patent office at the same time another similar patent application is submitted; an "interference" is supposed to be declared between them. The Examiner then decides which patent is given priority based upon who was first to invent and tried to manufacture their idea.

In this case there were apparently three applications in the office at the same time belonging to Homer Brooke, Robert Hemingray and James M. Brookfield. By some mistake, Homer Brooke was granted his patent under a different class, without an interference being declared between his and the applications of Hemingray and Brookfield. Brookfield has admitted that Robert Hemingray and Homer Brooke have both preceded him in their inventions. So the main dispute is between Hemingray and Brooke.

The record of the hearing from the Official Gazette follows:

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With this testimony, we now know that Hemingray produced threaded insulators around August of 1868. He later made a "great number" in May of 1869. He applied for a patent January 3, 1870; which wasn't granted until December 19, 1871. (See following page for patent drawing.) This leaves a total gap of over three years in which he could produce unembossed threaded insulators. I would say those first ones were most likely the unembossed CD 127.4 insulators. The CD 127.4 also appears in the patent drawing for the December 19, 1871 threading process (applied for in 1870). These were probably Hemingray's version of the CD 127 style Western Union pattern made by Brookfield and others.

There is a chance that Hemingray also produced the unembossed CD 131.4 during this time. I'm not sure which style came first. The CD 732.2, which is a threadless twin to the CD 131.4, appears in the patent drawing for the Floyd pinhole. This patent was granted in 1867; a full year before Hemingray produced his first threaded insulators. Did Hemingray already make the CD 732.2 before Floyd used it in his drawing; or did Hemingray make the CD 732.2 to Floyd's design? I have not heard of a CD 732.2 that does not have a Floyd style pinhole. If anyone knows of one, that will probably clear up the mystery. (The Floyd patent drawing is pictured on the following page.) 

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The Floyd style pinhole is also known on the CD 732.2 with the December 19, 1871 patent date (see CJ, June 1993). This piece was obviously made after the 1871 patent, Hemingray could have used their unembossed CD 732.2 Floyd molds to make un embossed CD 131.4 's, using a threaded mandrel. They then could have engraved the molds with the Dec. 19, 1871 patent date and received an order for more Floyd's. Thus an insulator with the 1871 date made to an 1867 patent.

Homer Brooke, on the other hand, conceived of his threading process during the winter of 1867 and 1868; probably 6-8 months before Hemingray actually made his own insulators. Brooke made a drawing of the invention when he thought of it, then tried to sell it. In February of 1869, he inquired about building a model for the patent office. In June of 1869 he tested it at Brookfield's shop after which Brookfield ordered a machine. Brooke then filed a patent application on December 11, 1869. 

The Examiner of Interferences in the first hearing felt that Brooke had conceived of his invention first and should get priority. The Board of Examiners-in-Chief felt that Hemingray was the first to produce items under his invention, so he should get priority. This appeal was objecting to the Board awarding priority to Hemingray. Although Hemingray was first to employ his invention in threading insulators; Brooke was first in conceiving it. The Commissioner decided to reverse the Board's decision and award priority to Brooke.

The outcome of this decision had a large impact on insulator production. Homer Brooke was able to sell rights to his patent of January 25, 1870, which appears on 14 different styles of insulators made by both Brookfield and other manufacturers. Hemingray was also able to keep rights to his patent although he wasn't able to claim his patent came before Brooke's. Both Hemingray and Brooke continued their involvement with glass production and become legends in glass manufacturing history.