CD-241, FRED M. LOCKE (and his Pyrex Connection)

Reprinted from "Crown Jewels of the Wire", December 1989, page 6

I first learned about this insulator and Fred Locke's possible connection with Corning's boro-silicate Pyrex glass several years ago from Lew Hohn. Two of the three known specimens were at the Houston National in 1988. The specimen shown in the photograph below is a light sage-aqua and the second specimen is identical. The third specimen (pictured on the fourth page) was in a display at the Houston National. It is a light lemon-clear glass. All three insulators have an extended inner skirt and the upside-down embossing as shown below:

Front:    PATD BY F.M.LOCKE
VICTOR
N.Y.

Back:    MARCH 31 1914 FEB 2 1915
OCT. 12, 1915

While there has been considerable speculation as to the manufacturer, due to natural curiosity and the unusual glass colors, it should be understood that such speculation is futile. As you will see after this discussion, the glass cannot be like other standard production.

The patent dates on CD-241 were granted to Fred Locke for boro-silicate glass (more on these patents later). This type of glass is now commonly referred to by the trade name "Pyrex". The Pyrex trademark was registered to Corning Glass Works on May 5, 1925. The application for the Pyrex trademark stated that the Pyrex name had been used since June 16, 1923 for electrical insulators and electrical insulating compounds. However, I am fairly certain that CD-241 was not made by Corning.

The research into Locke's possible connection with Corning's boro-silicate Pyrex glass is quite complex. This article was written in an effort to document the information, and I hope that it will also be interesting. We may never know with certainty if Fred Locke's patents for boro-silicate glass were indeed used by Corning and initiated their use of Pyrex glass for insulators.

It is unknown why Fred Locke left the Locke Insulator Corp. in late 1903. One speculation is that his company became too large for him to manage and still have time to experiment with new ideas. While his obituary said that he retired in 1904 (at the age of 43), he did become associated with the Lima Insulator Corp. when that company was formed in 1904. His name appeared in various trade journal articles in direct association with the Lima Insulator Corp and he may have acted as a consultant for them. That association was soon ended when the Lima plant burned in 1908.

However, Fred Locke remained very active in experimentation with various insulator designs and material compositions. He was granted 56 patents from 1889 to 1933, 32 of which applications were filed after he left the Locke Insulator Corp. I recently discovered seven of his last patents after a lengthy patent search as the result of a tip from Jeff McCurty. [Jeff's interest in Corning and CD-241 prompted a chain of events leading to the writing of this article.]

Fred Locke was undoubtedly well compensated for his share of the company when he left. His obituary stated that he maintained a large laboratory at his home in Victor, N.Y. There he surely spent countless hours experimenting, initially with new insulator designs. Soon he was experimenting with adding boron to clay mixtures to increase the strength of porcelain insulators. After promising results, he then began experimented to see if boron would also improve the properties of glass.

After initial successes, from about 1909 until 1917, Fred was engrossed with finding the right formula to strengthen glass by adding boron to glass batches and he attempted to cover all possible bases with a number of patents for boro-silicate glass. Then, until his death in 1930, he apparently was searching for a way to make colorless boro-silicate glass.

Fred Locke was granted 12 patents using boron compounds in the manufacture of porcelain and glass insulators to improve the electrical and temperature resistance properties.

Most of these patents deal with broad claims of using boron in both porcelain and glass insulators. All but a couple of the patents are indistinguishable as the text is nearly word-for-word with only minor changes. Patent #l,225,147 described testing 10" suspension disks made from the new glass. Patent #l,233,486 gives specific glass formulas for actual insulators that he used for experiments. It also claimed making clear (colorless) glass by adding the nitrate of either potassium or sodium. The making of cheap, clear glass may be the key to Fred's involvement with Corning.

My guess is that Fred initially experimented with improving the electrical properties of porcelain insulators. Then, later, after seeing the success he had with porcelain, decided to see if the electrical properties of glass could also be improved by adding boron. That much is fairly evident when reading the initial patents where the emphasis is on porcelain insulators. Early trade journal articles (shown later in this article) about Locke's new insulator material refer to "transparent porcelain" and "boro-porcelain".

Fred still had in mind making porcelain even though the products shown in the trade journals were obviously glass. He evidently had sufficient equipment in his laboratory to make insulators for testing purposes -- suspension disks, bushings and clear glass tubes. It was even stated in one article that the "...material is being placed on the market by Fred.......". That does not necessarily mean that he was selling insulators, but could merely indicate that he was trying to market the patents.

The three known insulator specimens of CD-241 were probably made in his private laboratory! Knowing Locke's great desire to show all the current patent dates on an insulator, the three specimens were probably made between October, 1915 and May, 1917. Locke would surely have marked them with the three 1917 patent dates if they had been granted before the insulators were manufactured. The three patent dates shown on the insulator actually represent five patents.

It is known, through present day Locke relatives (via Lew Hohn's contact with them), that Fred received royalties from Corning Glass Works for "many years" for his glass patents. Corning was also working on glass formulas with boron compounds as early as 1914. Their second patent was clearly interested only in various laboratory dishes and glassware. Since Corning was also working on boro-silicate glass formulas, they may have purchased the rights to Fred's boro-silicate glass patents to protect their use of boro-silicate glass in Pyrex products. We may never know for sure if Locke should be credited with patenting Pyrex glass since his glass patents were before Corning's glass patents, but his obituary in 1930 stated one of his greatest accomplishments was "...heat enduring glass."

Jeff's contacts at Corning said that Pyrex glass was the result of their 1919 patent. Commercialization of Pyrex may not have been practical until their 1923 patent which coincides with the development of the Pyrex trademark. The Corning patents are:

Corning wanted a clear boro-silicate glass but they could not find a way to make it cheaply. Iron, naturally present in sand, produces a green (aqua) tint to ordinary glass and a yellow tint to boro-silicate glass. While either manganese, nickel or selenium were used to decolorize (make clear) ordinary glass (with excess quantities producing pink or SCA glass), these elements would only intensify the yellow tint of boro-silicate glass making it amber. Corning's 1923 patent used neodymium oxide to overcome the yellow tint and produced a clear bore-silicate glass. This compound must have been expensive in the quantities needed for production. The patent called for a commercially available source which only partially contained neodymium.

Corning's boro-silicate patents showed only an interest in laboratory dishes. Jeff McCurty's research into Corning's history indicates that they had ideas to use glass for insulators as early as 1913, started working with suspension insulators in the early 1920's and had no interest in pin types until around 1925. The first sample pin types were not made until 1926. Could Corning have become more interested in making insulators after being approached by Locke in 1926 with the solution to producing a cheap, clear boro-silicate glass? Locke's last two patents may be the key to Corning entering into the insulator business. Note that the first patent was filed in early 1926 -- the same year that Corning produced their first pin types samples.

One of his five sons, Fred J. Locke, joined him as a co-worker in his laboratory, probably around 1920, and was named co-patentee on four patents. Fred N. Locke and Fred J. Locke had their crowning achievement with their last two patents:

Both patents were assigned to Corning Glass Works. These are the only Locke patents known to have been assigned to Corning. Others may have been purchased by Corning. A very interesting note is that both patents were granted after father and son had died. Fred's wife, Mercie P. Locke, was listed on both patents as the executrix and administratrix. Fred M. Locke's obituary stated that he died on April 16, 1930 at his home in Victor, N. Y. just 8 days short of being 69 years old. The recent death of his son and co-worker, Fred J., on March 7, 1930 "...undoubtedly shortened the life of the inventor who vas the originator of many devices and materials besides two which are of paramount importance, the Locke insulator and heat enduring glass." The "heat enduring glass" evidently referred to boro-silicate glass. Note that the last patent granted to Locke was filed nearly a year after is death and was a continuation of a patent application they had filed July 18, 1929. Corning may have become interested in Locke's last two patents as the result of the economical method to produce colorless boro-silicate glass. However, Corning's interest in these two patents may have been the superior optical quality of the glass -- better transmission of ultra-violet light -- and the ultimate use in the mirror for the 200 inch Mt. Palomar telescope manufactured by Corning in 1934.

It appears from Corning's vast patent record, during the years 1915 to 1930, that their major interests were lens for automobile headlights, opaque flesh-colored glass, glass that would absorb ultraviolet light, colored glass, vases and many different types of serving and cooking dishes, bowls and cups. It was not until after Locke's 1926 patent application for producing economical colorless glass that Corning entered into the pin-type insulator manufacture. Is there a connection here?? Corning's "Pyrex" tradename has been used to cover the manufacture of many boro-silicate glass formulas including insulators, laboratory ware and ovenware.

The variation in color of the three CD-241 insulators (sage-aqua and light lemon-clear) is undoubtedly due to different glass formulas with which Fred was experimenting and the persistent impurity of iron oxide in the sand. The glass would naturally appear like no other standard production, and could not be compared with any manufacturer's production to enable one to guess the name of the manufacturer. These insulators were probably made for experimentation by Locke in his laboratory.

To further show Fred Locke's interests with his early boron formulations for glass and porcelain, copies of the following trade journal articles are included:

I want to thank Jeff McCurty for his assistance in this project. He supplied the "key" tip (as well as other information) from his source at Corning, namely, that Locke had patented Corning's Pyrex "Flameware" glass in 1925. Without his tip on this unknown Locke patent, many of Fred Locke's last patents would not have been discovered by me, and the story as we know it todate would have yet to be written. Corning bought the rights to this glass patent and later worked on the tempering process. Pyrex Flameware was first used for cooking dishes in 1936 and later in the Apollo and Gemini space programs and the X-15 rocket plane. This is another "heat enduring" glass referred to as alumino-silicate glass. It is high in alumina, low in silica (sand) and contains no boron compounds. The patent is:

The following is from Electrical World dated 4-3-1915.

The following is from Electrical World dated 6-24-1909.

The following is from Electrical World dated 5-29-1915.

The following is from Electrical World dated 1-8-1916.