Dear Jack: 

I recently acquired at an auction two very bulky and crudely constructed suspension insulators (see below). The glaze is grey with streaks of blue, and there are no markings to identify the manufacturer. 

When I first saw these in a crate, the first thing I noticed was the odd metal fixtures on the top and bottom. These 8- prong spiders are leaded into holes in the disk.

Any information you could provide about these insulator would be greatly appreciated -- how they were used, identity of the manufacturer, whether they're considered scarce. 
Steven Kella 
2501 Shettler Rd. 
Muskegon, Mich. 49444

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I've received about two dozen queries on these in the past ten years. We've run the answer in CJ before, but I guess a repeat answer here might be helpful.

Dear Steven: 

The suspension insulators you have are meant to be used in the customary fashion -- assembled in strings to achieve the desired degree of insulation for transmission lines. 

These particular ones were made by the Jeffery-Dewitt Insulator Co., Kenova, WV. Their standard glaze color on suspension insulators and all pin types rated over 23 Kv was this "J-D blue" glaze.

This company was established in 1915, mainly on the basis of making this patented style of suspension insulator disk. These and other high voltage insulators were made by them by the casting process. The design is a horrible one, since the disks are inherently operated with the porcelain in tension, as opposed to the conventional cap-and-pin type of suspensions which place the porcelain in compression under load.

Not too many years after these were in wide use, they began to fail in alarming numbers, and the industry replaced them wholesale fashion with established designs which had been proven reliable. This event was nearly the undoing of the company in one swoop, but it struggled along until finally closing down in the 1940's.

Most (but not all) of the J-D high voltage insulators are marked with the manufacturing date such as "Mfg Aug 17 1931". Even without a marking, they are identifiable because of this really oddball design, plus the characteristic glaze color.

These J-D suspensions are not scarce in collector circles, many having been saved just because they were so unusual. 

Now, in case any of you are wondering how the porcelain in a conventional suspension insulator design is operated in compression when the top cap is pulled up and the bottom pin pulled down, see the sectioned view below. The pressure surfaces of the overlapping cap and pin create a compressive force between each other when the insulator is weight loaded. Even if the entire radiating porcelain shell is broken away, the insulator will not fail mechanically.

Jack

NEW PORCELAIN BOOK

Collector's Guide to Pricing Porcelain Insulators, by David Bethman 1982, softbound, 8-1/2" x 11" , 50 pages, $6 plus $.63 shipping -- from the author at 3307 Bennett Drive, Bellingham, WA 98225.

This is the first comprehensive and easy-to-use pricing guide ever published for porcelain pin types. It contains 1240 "line" items listed by style (U- number), marking, glaze color and value. An additional column serves as a checklist feature, and the left-hand facing pages are unprinted so they can be used for making notes on your particular specimens.

The frontal text material also includes eight pages for a compact summary of all the markings used on porcelain pin types -- a super handy tool for any beginner or intermediate collector not instantly familiar with all the many markings he will encounter.

The price listing covers so many specific insulators that virtually any insulator you will ever encounter will be shown there. For the sake of practicality, the list excludes the many very common styles with common markings and common glazes, all of which are usually valued at $1 or less each.

I have spent considerable time studying the prices shown in the book and found them to be remarkably accurate throughout the list. The pricing level is middle-of-the-road for sticker prices you would see at any current large insulator show or on sell lists of active collectors. I highly recommend this book be obtained by all collectors -- from the beginners to advanced. I would put it on the absolute "must" list for any collector or dealer who buys or sells porcelain pin types, even occasionally.

Jack

Ref page 21 of the July 1976 issue of CJ, John Hall (Ohio) stated that the Bennington museum in Bennington, Vermont had on display several styles of porcelain insulators formerly made by the Bennington Company, but that these were ordinary styles of threaded pin types.

We have spent so much time trying to establish whether or not Bennington made the old threadless items that the impact of John's revelation must have been lost in the shuffle. It would be extremely revealing and important to know what specific insulators they did allegedly make!

So I now repeat my 1976 appeal that some eastern collector visit Bennington to determine the U- numbers and identifying characteristics of those specimens. This would be really super info -- worth two gold stars. 

Jack

Dear Jack: 

I can't seem to be able to find any information on these two insulators (above). Could you please let me know what your know about their rarity, origin, value, etc.? 
Rex M. Vaughn, NIA #520 
Anderson, California

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Dear Rex: 

The large insulator with lag screw mount is a slack-wire tree insulator cataloged and sold by Line Material Co., and the L-M marking appears on the porcelain part of it. The recess-embossed "U" marking on the porcelain part indicates that was made for L-M by Universal Clay Products Co., Sandusky, Ohio.

Interestingly, the designers of the porcelain part made a gigantic goof. The catalog says to install it, you screw it into the tree with the top groove ending horizontal, insert the wire, then wrench the screw a half turn to the right to lock in the wire. But the ears on the porcelain point in the direction which require a half turn to the left to lock the wire -- a poorer arrangement.

For other physical mounting arrangements, the porcelain can be oriented 90 degrees differently in the steel yoke.

Your little black insulator (also comes in brown) shows up every once in awhile in collector circles. As far as I know, it's still a "whatisit" -- which is a much classier name than "gismo". Gerald Brown shows this item on page 132 of his 2nd Edition and repeats without comment the hearsay info (guesses?) that it was an "attic insulator" or possibly used in neon sign installation. 

We would appreciate hearing from any CJ reader who knows for sure the intended use of this gadget, insulator or otherwise. Wild guesses won't count. 

Jack

FOREIGN PORCELAIN INSULATOR BOOK 

Here's advance information on this book being coauthored by Marilyn Albers (Houston) and this writer.

We have been frantically working on this book since last summer and thus far have made over 300 of the scale drawings for its style chart -- about 3/4 of the drawings that will be made for the initial edition to be available early this summer. As with all previous insulator reference books, the idea is to somewhere draw the line and publish the information at hand as a starting point. Then, anything not shown in the book can be considered new and needed material. 

The book will be similar in format to the familiar "Porcelain Insulators Guide Book" on U.S. insulators -- the frontal material explaining the foreign practices and the special insulator designs and uses etc., followed by the complete style chart of all foreign porcelain pin types, then the information on all known manufacturers and markings attributed to each one. As with the 1981 book on foreign glass insulators by Marilyn, this one will have an appendix tabulation of all styles showing what manufacturers and markings are known for each one.

Since we let the cat out of the bag some time ago about the pending publication of this book, it's evident a number of collectors are champing at the bit for it to appear. Be patient; it won't be long now. Before even this first edition is done, I estimate Marilyn and I will have spent over 1400 people-hours on it, plus some considerable expense for all involved in its making. If even 200 people end up using the book, that means we've spent 7 hours working on it for each one who'll benefit from it. A labor of love?

Jack

Dear Jack:

... and I also found this small aqua glass insulator while digging for insulators and bottles in the old city dump here at Starke. It appears to be some sort of a bushing. Do you know what it is? 
Malcolm Sanders, NIA #1567 
Starke, Florida

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Dear Malcolm: 

This insulator is for lightning rods -- and I presume to insulate the conducting rod from the metal mounting stand. This and very similar versions were also made by a number of porcelain companies. As lightning rods and accessories are, these bushings are collector items.

Jack

Dear Jack:

In your book you state that the U-239 embossed Thomas is not common. I have a few of these which are very crude dry process and no doubt old. Of interest here though is the fact that on the line where I got these, the embossed ones are not common, but each pole has at least two insulators which look like they came from the same mold (same glaze too) and yet are not marked. Could these also be Thomas, Incidentally, what would be a fair value for the embossed ones?
Emory Snyder
White Haven, PA

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Dear Emory:

The appeal of the Thomas U-239 and U-294A with the embossed (raised) markings is mainly that, other than older O-B wet process items, embossed markings exist on only several items. One case is these Thomas items, and the other is the MACOMB marking found on the early Illinois dry process items. Add to this the facts that these Thomas items are scarce items, they were made in the 1907-1920 period and represent the very few styles ever made dry process by Thomas. I'd guess that either of these Thomas items would be $5 items but I think the U-239 is the most common of the two styles.

You're probably correct that the very similar ones unmarked are also Thomas. That characteristic crown with the long, arched smoothing marks exists on ponies, exchanges and transpositions. All these telephone styles are quite similar as to glaze and fabrication details, so we've long regarded them as Thomas because of the ones such as yours which are marked THOMAS.

Jack