ICON articles extracted from the mailing list

Origins of the RD Number Insulators

Compiled by Donald R. Briel

09 Jan 2004

Ian Macky wondered..

My memory was that the origin of the apparently British "RD" (Registered) insulators is still unknown. Is that so? I asked my new glass contact about them, just in case he had any ideas. Here is an excerpt of his reply:

"RD 149959 - 22 May 1890, registered by James Bridger, Upper Edmonton. Glass Merchant.

RD 154745 - 20 August 1890, registered by F.H. Davy & Co., Upper Edmonton. Glass Merchants.

Also watch out for RD 154744 - 20 August 1890, registered by F.H. Davy & Co., Upper Edmonton. Glass Merchants. This could be anything, but most likely is a slightly different insulator.

These insulators were probably made by one of the NE glassworks, located in a band from Yorkshire to Tyneside. Colored pressed glass is unlikely from the NW glassworks around Manchester. My transcription of Merchant / Merchants is accurate.

Edmonton was an old coaching town, the first staging post about six miles north of London on the Cambridge Road. Edmonton is on the western side of the road. Upper Edmonton is a smaller community on the eastern side. By 1890 Upper Edmonton was a London suburb, a busy mix of residential, commercial and light industrial properties.

Why insulators? Perhaps it was the location of an important node on the telephone system - same rationale as coaching town, different century. Fresh horses and change here for other destinations. Fenny Stratford, the first coaching town south of Stony Stratford on Watling Street, was also the location of a major switchboard and booster on the telephone network."

This is all news to me, and fantastic information. Is this news to everyone else? Try searching for "RD 149959" information and there's nothing at all, certainly not the above. Also, how about that potential third RD insulator!


Elton Gish comments:

Yes, it is all new news to the hobby!! Thanks. I'm curious about your new "glass contact". How was he able to come up with this info so easily? What reference source did he use? Are there any associated documents, drawings, illustrations, photos, etc. that he found? Caleb probably would like to know since it concerns foreign insulators. Does the "registered" mean a patent was issued later? What is meant by "registered"?

Dwayne Anthony comments:

Actually, I recall seeing the information previously posted somewhere on the three registered RD numbers and probably have it in my files somewhere. Was it someone here on ICON that posted it? I also recall that the person that posted this information threw out some speculation that the third Rd number could be a CD 134.

Anyone have a count on the number of 133 RD's in collector's hands? I only know of two. The CD 126 RD's are a little more plentiful, but still considered rare...I'd guess a dozen or so, in varying condition.

These are photos of the CD 126 and CD 133 RD insulators.

CD 126 RD Blobtops
CD 126 RD Blobtops
Two variations: (left) milky jade green aqua; (right) green aqua with small to moderately sized snow chunks. Both specimens have the typical ground base. The jade specimen has rounded embossing; the snowy one has prismatic embossing. This provides proof that at least two molds existed. A consensus from longtime collectors estimates that 15-20 of these exist in varying conditions from vnm to extremely fractured. The milky jade appears to be the most prevalent. One milky jade specimen exists with a metal pin still encased in the pinhole and a full-length vertical fracture. Use of metal pins could be the culprit for the handful of fractured CD 126 RDs known to exist in collections today. (For a pic of the CD 133 RD insulator [id=79131212].)

Rare CD 133 RD Signal
Rare CD 133 RD Signal
Four specimens of this style have been confirmed. The embossing on the one pictured above is prismatic. It has the ground base, which is also characteristic of the CD 126 RD style [id=79130728].

Ian Macky comments:

I am as curious as you and the rest of us. Will report back with more soon. I don't know what his magic reference was, but I must have it. He solved a problem that stumped us for years in just moments.

Ian Macky comments:

My contact recommends the following sources for United Kingdom registration information. He quotes:

a.. Thompson - The Identification of English Pressed Glass 1842-1908 b.. The Glass Association - Registration Numbers 1908-1945 c.. - the best of the manufacturer-specific websites, particularly open up "George Davidson & Co" in the menu window on the left - but the whole website including Chris's newsletters are worth studying for research techniques. d.. - the only serious discussion forum. This goes back years. Lots of useful material and some very heated debates. You should be using it. Full of pointers to other resources.

Paul Greaves comments:

I remember the same thing, including the reference to the CD 134 ... but I can't place it. I am posting this here for the sake of adding support to the claim that someone somewhere did find this information before. If I can place it, I'll post the reference.

Jim Sinsley comments:

I believe the "RD" stands for: Registered Design.

I have some British made bottles with similar embossing and it always seems to be a six (6) digit number. It would seem a simple task to have one of our British friends do a little research but I have never been able to find anyone to help with the bottle identification information. Perhaps someone else could get some cooperation.

John Graham comments:

I searched through 23,000 saved ICON messages dating back to 2001. Here is the only relevant posts on the RD insulators I could find.

Mark Grimek comments:

According to the London Patent Office both CD 133 (RD #154745) and CD 134 (RD #154744) were issued to F. H. Davey & Co., Edmonton Glass Works, Upper Edmonton, London on August 20, 1890. CD 126 (RD #149959) was issued to Glass Merchant James Bridger, Mead House, Upper Edmonton, London on May 22, 1890. It is possible that James Bridger was an agent for the F.H.Davey & Co.

As to where the RD embossed units were found : CD 126's - 6 from New York State, with others in Georgia and Nevada. CD 133's - at least 2 known, one found near Mystic, Connecticut CD 134's - none known to exist in collections. {No ICON members emailed they had one}

Colors range from: Aqua, Green Aqua, Milky Green Aqua, to Jade Green Milk glass.

Jack Kesling comments:

I note with interest Mark Grimek's note on the RD embossed insulators. I was lucky enough to find two CD 126 RD #149959 in deep jade green milk glass on the Central Georgia Railway telegraph line in 1969. They were heavily sooted and had cut sections of old heavy gauge iron wire. They were located on the section between Fort Valley and Macon - actually very close to Macon.

I was not able to tell the color until they were cleaned. I remember being amazed by both the color and the fact that the base on both insulators were heavily ground down on a polishing wheel. At that time, I did not even have a book that had the CD listed. One of these insulators was traded to a person in New York state - I think the name was Brad Cook, but it's been a long time ago. I remember I traded the Boston screw top - light mint green in color - to Brad Cook for a National Insulator screw top. At that point in time, I had no idea of the value, just that the insulator I received was odd looking and was a nice addition to my collection. I still have the second CD 126 RD in my collection. Various people have speculated that many of these odd insulators came from old lines in the Northeast and were sold cheap and were used as replacement insulators on the Central Georgia line. Although I have no clue how these insulators got on the line, I can definitely confirm that at least two CD 126 RD's indeed came from Georgia.

Richard (Dick) Bowman comments:

Just a couple more tidbits on the RD's: For the record, I own one of the CD 133 RD's, so do not know if that is included in Dwayne's count or in addition to it.

Regarding the CD 126's, I have owned four (4) of them and a common characteristic of them is a sloppy & loose pin fit even though they are certainly a US pin style. I found the postings on their origin very interesting. I recall hearing & reading over the years that they were of English origin, but the postings tell a better story.

They were also used in the Northeast as my son, when he was about 15-16, found some poles on the ground near a highway in central New York and one of the pieces on the downed pole was a CD 126 RD.

Perhaps some of you remember Jerry Kowalski, an old time collector from around the Pittsfield, MA area. I bought a CD 126 RD from him around 1970-71 and as I recall he had two to four more of them. Perhaps he was issued a visa so he could leave New England as Pittsfield is close to the NY border.

My gut feeling is that there are more than the dozen CD 126 RD's floating around as between the four to five our familiy has had plus those that Jerry had plus the few that I have seen off & on over 35 years, the figure of a dozen seems a tad light, but not by a great amount. Has anyone ever seen a CD 126 RD that did NOT have a ground base? I have not, but I am curious.

Peter Abbott comments:

For what it's worth, I've owned three each of the CD 133 and CD 126 RD insulators. Two of the CD 133s came from a collection in central Vermont that was mostly put together locally, meaning that I strongly suspect (but have no way of knowing for sure) that these pieces came from the VT/NH/ME area, or perhaps upstate NY. Also, those two CD 133s had light blue paint on them leading me to suspect that they may have been seen service on the side of a house or other building.

Doug MacGillvary comments:

While we still are talking about RDs, let me add this...The first CD 133 RD I saw was at a Pole Cat show in Glastonbury, Ct. probably mid 1970s. Bob Irons, a bottle dealer from the New London area, sold the piece to Hank Goulet, then a collector from Old Lyme, Ct. I remember Hank writing a short article for Crown Jewels about the RDs.

John Graham comments:

If these are foreign then why are they listed in the North American price guide? Why not list these as foreign insulators in GIFONA instead? If it is because they were found in America then this is inconsistent with the way the CD 122 VMR/Napoli insulators were treated - the VMR Napoli's are currently listed in GIFONA and not in the McDougald price guide, but my understanding is that they were found in America.

Eddie Lewis comments:

That's a good point John, Actually the VMR CD 122 & CD 122.6 were in the 1995 price guide and the 1999 price guide states the following in the preface, "Even though the CD 122 was manufactured for use in the U.S., we do not believe that it should be included in this listing since it is of non-North American manufacture." I suspect the same thing will happen with the RD's once it is verified that they are of British manufacture, especially now that you put a bug in Caleb's ear. What I do not get is why US companies would use foreign glass. Was it really that much cheaper or easier to get? I assume because of their apparent scarcity, that these RD's were used as replacements. The VMR Napoli was made in Italy and yet was manufactured for use in the US. Did they come along after Kerr had made their last CD 122? The CD 126 & CD 133 are some of the oldest known threaded insulators and it does not make sense that they would be in Georgia.

Caleb Thimell comments:

These British manufactured and Registered (RD) insulators are clearly foreign. I plan to include them in the World Wide Glass Insulator Supplement and Price Guide that I am currently working on. My guess is that until the information was confirmed, they were assumed to be North American since that was where they were found in service. The CD 122 VMR/Napoli insulators were found and used in the U.S. and were originally listed in the earlier McDougald price guide. However, they were removed from the latest edition after they were confirmed to have been manufactured in Italy.

If anyone obtains further information on these British registered insulators, please contact me privately with the information so I can be sure to include the details in the book.

Ian Macky comments:

Define your terms. What is foreign? The RD's are an American CD, made to American specifications with American threads, imported and used in America. Does this sound like a foreign insulator? The price guide covers "North American glass pintype insulators", which does not help. I would take "North American" to mean "used in North America" not just "made in North America".

John Graham comments:

I disagree with Ian - I think North American insulators means just that... made in North America. I guess it's really up to Caleb since he is writing the new "foreign" insulator book.

Bill Meier comments:

Well, it is probably up to both people, as it would be strange to have the same insulator listed in McDougald and GIFONA... Well, there will not be another McDougald price guide for several years or more, so the issue will be quiet... If Caleb claims it, I suspect it will be removed from McDougald.

Ian Macky comments:

My point was that the semantics of "North American" is undefined by the price guide. They do not say what they MEAN by "North American", so we can only ask, guess, or make our own decision.

Lee Conte comments:

Actually it means even more than that. It means the company who manufactured it is headquartered in North America. If you drive a Toyota, do you say a Toyota is an American car? No. (Not even if it's made in America.)

James Doty comments:

Here is a photograph of my RD insulator.

[Picture not available]

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