Lewis self-binding insulator

[Trade Journal]

Publication: The Electrician & Electrical Engineer

New York, NY, United States
vol. 4, no. 6, p. 203, col. 2



In his article on the construction of lines for electric circuits, Mr. Thomas D. Lockwood, on page 89 of the March number of this journal, referring to the Lewis self-binding insulator, states that the conception of forming the outside screw in a direction opposite to the internal screw, in order to provide for the simultaneous attachment of the insulator to the line wire and the pin, is due to Frank L. Pope. This statement although technically correct, inasmuch as the device was patented to Mr. Pope on December 25th 1883, in justice to Mr. Lewis, requires an explanation. The invention was original with Mr. Pope, but after the issue of his patent, he for the first time learned that Mr. Lewis had at an earlier date conceived the same invention, and had embodied it in insulators manufactured under his supervision in England. While this circumstance does not of course impair the validity of Mr. Pope's patent, yet there can be no question that Mr. Lewis was a prior and independent inventor of the same device, and it is a matter of simple justice that he should have due credit therefor. In preparing his article, Mr. Lockwood of course had no access to other sources of information than those afforded by the records of the United States Patent Office.


Keywords:Insulator : Slater Lewis : Pope : Self-Tying Insulator
Researcher notes:While the scenario stated in the article may be true, the evidence does not bear this out. It is a fact that Mr. Pope was the patent attorney for Mr. Lewis on Mr. Lewis' patent application dated May 2, 1882 with patent granted on May 1, 1883. Mr. Lewis' patent was for threads on the top of the insulator with the same turn as those in the pinhole, which prevents screwing down the insulator and engaging the tie-wire loop at the same time. Mr. Pope's patent application was dated May 23, 1883 twenty-two days after the Lewis patent was granted. Mr. Pope's patent called for reverse threads on the top of the insulator which did allow screwing down the insulator to engage the tie-wire loop and the threaded pin at the same time. While the insulators produced by Mr. Lewis in Europe had reverse threads, his U. S. patent did not. It is obvious that Mr. Pope discovered the error in the Lewis patent while he was working as Mr. Lewis' patent attorney, and later claimed the correct threading as his own novel idea in his later patent application.
Supplemental information:Article: 5387 Patents: 276,839; 290,922 (see patent gb1882-0001017)
Researcher:Elton Gish
Date completed:January 30, 2009 by: Elton Gish;