This is Alfred Bicknell's sash-cord guide ("pulley"),
Patent No. 83,685,
issued November 3, 1868, and reissued March 19, 1872 as
RE4809:
He actually invented this a little earlier: it was exhibited at
The Tenth Exhibition of the Massachusetts Charitable Mechanic Association, at Faneuil and Quincy Halls, in the city of Boston, September, 1865:
reports of the Judges on page 59 lists "Alfred Bicknell, Boston.
New England Window Weight Pulley. Good for light sashes. Diploma."
In 1870, it won a third [place] medal and certificate at the
38th Annual Exhibition of the American Institute. The
1872 Boston Directory lists
the company's address as "39 Bowker". They appear to have been out of
production by about 1885.
I have a set of four, and have seen only a few others for sale (sometimes
mis-identified as wire-guide insulators), and a Maine antique dealer
reports finding 3 clear and 52 aqua ones at an estate sale. They are
uncommon. The embossing on mine reads
"PAT. NOV. 3 68" on one side and
"NO 2" on the other. Presumably there are
several sizes, but only #2 is known for sure: its dimensions are
1 13⁄16" (47mm) long and
1 3⁄16" (31mm) diameter.
They were alternatives to the typical metal pulley-wheel guides used
in older single and double-hung windows which use a sash-weight on a
cord as counterweight:
My invention has for its object to furnish an improved
anti-friction grooved guide-block for window-sash cords, which shall be
simple in construction, inexpensive in manufacture, and effective in
operation, and which is designed to take the place of the ordinary
guide-pulleys.
My examples have the square notch (a³ in fig. 3 of the
patent), but the glass was introduced into the mold at that point so
there is a "pontil" left over which has not been ground off,
thus making the slots useless.
The Corning Museum of Glass has a photo showing them inserted into pieces of wood,
but it's not clear how they are retained in position.

Scientific American, Vol 20 · 1869 |
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BICKNELL'S PATENT AMERICAN WINDOW WEIGHT
PULLEY.
As the inventor says, the title of
"pulley" is a misnomer, the device being simply a segment—one
half—of a pulley; but the object intended is that attained by
the ordinary revolving pulley. The engraving shows the stile of a
window frame, containing a semi-disk, or half circle, made of glass,
grooved on its periphery to receive a cord, and having shoulders, or
rebates, on its sides and on the bottom to hold it in place. The
glass segment, A, is set in a mortise through the stile, B, and a
similar but narrower mortise—to conform to the reduced thickness
of the segment—in a bracket or supplemental stile, C. The
dotted lines at D show a thin plate of metal screwed on the window
frame to conceal that portion of the mortise necessary only to admit
the glass segment. No screws, pivot, plate, or recessing, beyond
the slot through the stile, necessary for ordinary pulleys, are
required; the segment being merely passed in from the front, and
then being held securely by the ledges on its sides and bottom
resting against the sides of the mortises.
The cord sustaining the window weight
merely slides in the groove of the segment over the smooth glass
surface, and thus all creaking of pivots or axles, so annoying to
the ill or nervous, and all necessity of occasional oiling is
obviated.
The inventor claims the following
advantages: Simplicity in construction and application; non-liability
to derangement, no screws; no letting in of face-plates; less
expensive than other devices; greater friction on the cord, but less
wear, requiring a less proportionate weight to balance the sash, and
giving a longer life to the cord; no rusting, and always in order,
not being affected by the weather.
This device was patented through the
Scientific American Patent Agency, Nov. 8, 1868 by Alfred Bicknell.
For further information, address
American Glass Pulley Company,
56 Congress street, Boston, Mass.
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| Glass Sash Pulleys.
From A. S., Nashville, Tenn.
— A short time since I saw a pair of sashes hung with weights and
cord, but in place of iron or brass pulleys in the frame the pulleys were
provided with glass thimbles. The owner of the house tells me that the
pulleys in question have been in use for over 15 years, and the cords are
as good to-day as when first put in. Can you inform me where such goods
can be purchased? If not, please refer my question to the readers of
Carpentry and Building.
Building Age, Volume 7, 1885
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Glass Sash Pulleys.
From L. S. H., Boliver, N. Y.
— Glass window pulleys were in use as far back as 1867, in South
Berwick, Me. They were employed by W. A. McIntyre, with whom I was at
that time serving my apprenticeship. They were manufactured by the American
Glass Window Pulley Co., and were furnished to the trade by B. D. Washburn,
No. 137 Congress street, Boston. The pulleys referred to I do not think
were identical with those mentioned by other correspondents of Carpentry
and Building; hence I give what information is in my power. I fear,
however, that it will be of very little benefit to the correspondent
inquiring.
Building Age, Volume 8 · 1886
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Glass Sash Pulleys.
From S. W., Newark, Ohio.
— Answering the request of "A. S.," of Nashville, Tenn., I would
say that while working in Grand Rapids, Mich., in 1873, glass pulleys
were being introduced, and were used in the building upon which I was
working at that time. They appeared to be the article. They were
noiseless and frictionless, the pulley being stationary, the rope simply
passing over by means of a hollow crease. The saving in the weight would
almost pay for the pulleys. I have a card that was handed to me at that
time and which has been laid away so carefully for preservation that I
only came across it a short time since. This card contains sizes of
sash, their weight, and the number of pounds of sash weights required
to run the same, using the glass pulleys. The goods were manufactured,
or at least sold, by A. A. Weeks, 105 John street, New York.
Note. — Our correspondent's
letter above afford very little information in addition to what is
already generally known in the trade. Mr. Weeks, we believe, has not
been in the business for a number of years, and, if our information is
correct, at the time that he gave up the trade the manufacture and sale
of the pulleys were commenced by a company in Brooklyn. They, too, have
passed out of action. So far as our inquiries go, glass pulleys are at
present entirely out of the market.
Building Age, Volume 8 · 1886
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