The Purple CD 134 - September 13, 1881 Patent Insulator
by Joe Maurath
Reprinted from "Crown Jewels of the Wire", May 1991, page 18
(The following article originally appeared in the January, 1991 issue of the Yankee Polecat Insulator Club
Newsletter.)
Perhaps the most exciting insulator find reported by club
members during the past year was a CD 134 lettered around its base
rim: PAT SEPT. 13,'81 in purple. This beauty was discovered in an antique shop
in central Massachusetts by Tony Longtin last summer.
After personally
examining this piece I've noted that this insulator appears to have been
very well made, since the glass has a distinct smoothness to its texture and the
glass itself has no crude qualities. The insulator's shape and base
lettering style are identical to CD 134 American Insulator Co. embossed units
and Tony's insulator has no traces of any previous lettering. Its color depth
is comparable to that usually seen in purple Whitall
Tatum No.1's.
Although the McDougalds had already listed this specimen in their 1991
Price Guide [due to the fact that Tony Longtin had called them just prior to
the books delivery to the printer and a last minute addition was made], I wasn't
aware of this variant's existence while compiling and writing the
histories of Boston area and New England glass insulator manufacturers for
Volume
1 of McDougald's Insulators-A History and Guide to North American Glass
Pintype Insulators. I have decided to prepare some thoughts about this
insulator's background and possible source.
The discovery of the purple CD 134 with only the Sep. 13, 1881 patent date comes to me without a
real lot of surprise, as I plan to discuss here. This patent covered a process
in which the insulator's threads were made within a separate glass thimble. The
premanufactured threading was then inserted within the
insulator's unthreaded pinhole cavity while the newly formed insulator remained soft and hot. This threading process patent was issued to
Samuel Oakman and was assigned to Edward Sherburne. There is no mistake
that Tony's insulator was threaded by this process after carefully looking at
it. Many of the earlier American Insulator Company (before about 1884) pieces
were similarly threaded.
Little doubt exists that Mr. Oakman was working for Mr.
Sherburne at the time the 1881 patent was granted, since Mr. Sherburne was the
assignee of Mr. Oakman's patent idea. At present, we have no other record or
evidence of Mr. Oakman's activities of the 1881-1882 period, and it is assumed
he was working at the Sherburne glassworks for at least a portion of that time.
Presently we have no evidence of any insulator production at Mr. Sherburne's
glass plant. However, it is known that Sherburne was a rather prominent
manufacturer of window glass during at least the 1880's and that his
glassworks existed in the Boston area.
Up until around the 1920's, manganese was
utilized in making clear glass, such as for windows and bottles, etc. Briefly,
the manganese when included within the glass batch offset the iron which was
naturally present which otherwise produced aqua colored glass. After years of
exposure to the sun's ultraviolet rays, a chemical reaction occurred within the
"manganese-clear" glass, eventually turning it purple. Clear glass was
more expensive to make back then, principally because of the cost of the added
manganese. Therefore, glass insulators made up through the 1920's generally were
aqua whenever the color of them didn't matter. Many of the purple insulators
made then were produced from excess batches of clear glass intended for making
bottles, window glass and so forth.
Although Mr. Sherburne was probably much
more interested in turning out window glass rather than setting up tooling for
making insulators, the purple CD 134 as described above very likely could have
been among some prototypes made at the Sherburne glassworks. It is entirely
possible that Mr. Oakman produced and set up one insulator mold there with
the necessary equipment in order to manufacture some experimental pieces
threaded by the 1881 patent process. Perhaps, too, Mr. Sherburne assisted and
took some interest in making these trial specimens.
If all of this is true, it
then would be obvious that the glass prepared for making Mr. Sherburne's windows
was also used, in producing the 1881 patent insulator prototypes (perhaps
"after hours" or whenever orders for windows were slow) which initially were
clear and later turned purple from the sun.
The above represents the most likely
and logical explanation I have for the purple 1881 patent insulator. If
proven true, then this insulator represents the missing link of Mr. Oakman's
insulator making activities of the 1881-1882 period. At some time during the
early 1880's (exact year unknown), Mr. Oakman began manufacturing his own
insulators with the 1881 patent threading. No doubt he either paid royalties to
Mr. Sherburne or purchased rights to the 1881 patent outright from him.
As
I described with other details within the McDougald's book, Samuel Oakman
officially "resurfaces" in 1883 at the American Insulator
Company in New York City. It is apparent that he continued to manufacture
insulators with the 1881 patent threading (most of which have American Insulator Co. embossing) up until sometime in 1884 or
so. On September 9, 1884
he was granted another threading process patent, which covered a collapsible
threading plunger. Later (1884 and after) American Insulator Co. specimens
appear to have been made by that process.
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