In the last PIN (September CJ) we incorrectly reported that the Pittsburg U-393A's were used on an old trolley line in Chattanooga, TN. Thanks to Ken Roberts (NIA #5962) for correcting the report. Ken said Charles Kocisek found the U-393A's in an abandoned substation house on the T.V.A. Reservation in Muscle Shoals, AL. The U-393A style is rare and glad we are able to report the correct information. All previous examples of this style are damaged specimens found in the Pittsburg dump over 20 years ago. 

Gary Scott (NIA #5758) reported a very rare and exciting find. Late last year Gary reported finding a very near mint U-945 "Mershon Type" in a barn in Watertown, New York!! Only six U-945's are known counting the one Gary found. The insulator has since found a new home with Jeff Kaminski (NIA #3582). I hope it is not too uncomfortable among Jeff's collection of large multipart porcelain insulators, many of which are 50+ pound 4-part multis.

For those of you not familiar with U-945, it is a 3-part glazeweld made by the R. Thomas & Sons Co. in East Liverpool, OH circa 1898-1903. Thomas patented the glazewelding process on March 8, 1898, which they called "glaze-filling". The incuse marking found only on U-945, "MERSHON TYPE / PATENT / JUNE 7, 98", refers to the Ralph D. Mershon patent No. 605,256 granted on June 7,1898, for the extended petticoat. Glass insulators made according to the Mershon patent also have raised ridges across the top surface of the outer skirt, which aid in directing rainwater away from the crossarm. U-945 only used the novel extended petticoat, which protected the pin from damp weather to reduce electrical leakage from the surface of the insulator to the pin. Thomas apparently produced U-944 based on this patent, too. Thomas was granted patent No. 601,195 on March 22, 1898, for an almost identical idea for the extended petticoat; however, the Thomas patent called for the extended petticoat to extend through the crossarm which was impractical. The extended petticoat through the crossarm would surely break with modest strain from the conductor. The Mershon patent application was filed five years before the Thomas patent. Evidently Thomas could not come up with a workable patent for the extended petticoat so they decided to license the Mershon patent.

It is odd that no U-944' s are marked or bear the Mershon patent date. We should point out that the white U-944's appear older (manufacture of white insulators ceased in 1901 reappearing in limited numbers in 1910's) and are 1/4" shorter than the brown glazed ones (difference in the length of the extended inner skirt). U-944 was shown in the 1904 Thomas catalog (but not in the 1907 catalog) being offered in either white or "chocolate color". The "chocolate color" is "brown"; however, most brown U-944's are very dark and somewhat unattractive. A couple ofU-944's have the early Thomas glaze that is mottled orange and mustard. The first brown glaze Thomas used was caramel-colored produced after white glaze became much less desired in 1901. This was followed by mustard and orange/mustard glaze. Our best guess is that the beautiful caramel glaze was produced circa 1901-1903, the attractive orange/mustard glaze was produced circa 1904-1907, and followed by darker glazes with lesser amounts of mustard and orange circa 1907-1910.

Brown U-944's were found on an old DC line that ran along the Fall River Road from the power station to Idaho Springs, CO. My records show that only five white U-944's have been reported and only nine brown ones. I do not know where the white U-944's were found. You might assume that the U-944 replaced the more delicate U-945. U-945 was not shown in either the 1904 or 1907 catalogs. However, it did appear prominently on the cover of a Thomas publication dated March 8, 1902, (see page 137 in my book, Fred M. Locke: A Biography) commemorating the victory over Fred Locke for Thomas' March 8, 1898, patent for the "glaze-filling" process and introducing their "glaze-filled" styles, U-928, U-928A, and U-945. 

The demand for Thomas "glaze-filled" insulators dropped dramatically with the introduction of cemented multipart insulators. This occurred just prior to Thomas moving much of their production of high voltage insulators to the old Westinghouse factory in Lisbon, OH in 1905. The 1907 Thomas catalog showed only three glazewelded styles: U-939B, U-967, and U-936. However, the illustration of U-967 does not match the dimensions shown for that style which more closely match that of U-956. All of the production of these glazeweld styles in the 1907 catalog would have the dark brown glaze. 

Keith Roloson (NIA #3201) reported a very unusual U-58 exchange. It is unmarked and made of dry process porcelain. At least it is unmarked in the conventional manner. This is the first pin-type porcelain insulator that I have ever heard of being marked in the top of the pinhole! There is a perfectly formed "5" embossed (raised) in the top of the pinhole!!! Keith checked all of his exchanges, I checked all of mine, and a couple of other people checked their collection. This is the only one like this we have seen. Please check your exchanges and report to me any similarly marked. It is not obvious which manufacturer made this insulator. An argument could be made for Square D but we cannot be sure.

U-58 with embossed "5" in top of pinhole.

Dennis Stewart reported a new multipart style. It has been assigned M-2617D. It has the incuse marking #1 (see page 128 of Jack Tod's book, Porcelain Insulator Guide Book) consisting of the Franklin Porcelain Co. name and round logo. The one in the photograph below has a beautiful mottled mahogany glaze. Dennis also found a second one with incuse "FP" marking on both the top and bottom shells.

M-2716D (9 - 7.5 - 3 x 6)
 with Franklin Porcelain Co. marking.