2149: Frame from a "Grandfather clock" (with a pendulum)
2154: My guess is that the ends are mostly there to help protect
the long thin thing(s) in the cylindrical part--say, during transport.
It appears sort of in the style of a musical instrument case--which
makes more sense than a shipping case due to the absence of a lock.
So my final guess is that it contains an instrument--perhaps one for
engineering, like a LEVEL, where accuracy is a virtue.
I would tend to doubt it, particularly if your definition of volume
was more than a few dozen.
I doubt it. But you're making quite a jump from "commercially in
volume" to "one off". For a small unit like that I'd imagine it was
used in scientific demonstrations in school settings, and inventor/
research labs. And maybe guys who were working on the development of
their Ming The Merciless Death Ray. In portable form. ;)
Cases like the one pictured were the equivalent of a blow-molded case
today. Now they're considered really good cases and of exceptional
quality, but back then they made them for everything.
Anyway, the Tesla coil was a guess, and I don't see how it could be
verified without actually having a picture of one with the coil inside
It's the 19th Century. You walk into a political caucus. The absence
of footprints in the fresh snow has told you that nobody has stepped out
for fresh air because it's very cold and nobody wants members to suffer
A boss spots your case, rushes over, slaps you on the back, and invites
you to the smoke-filled room in back. As he leads you across the floor,
others join you. Your reputation has preceded you.
You set up your invention and they stand in a circle gushing praise.
They agree that you will be the next President of the United States.
They don't shake hands but are definitely relieved to conclude their
The owner's description:
1. The terminals come into the case through some white insulating kind of
2. The exterior case is copper.
3. The terminals connect to two steel rods. They appear to be precisely
ground to size.
4. The two steel rods were separated by two pieces of glass (insulators?)
5. The two steel rods had blocs of carbon on the outside.
6. Two larger pieces of carbon were on the top and bottom of the above.
7. The entire assembly was wrapped in ordinary masking tape (no insulation
8. The space between the assembly wrapped in masking tape and the outer
copper shell was filled with powered carbon.
I still don't know what it was! If it weren't for the carbon (which is
conductive) I would think some kind of a capacitor.
Perhaps I am wrong about the solid carbon and the powdered carbon being
carbon... but it sure looks like it to me! Sure made a mess in my shop.
Anyone have an answer for it?
"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote in message
Thanks guys, the owner of the device thinks that this is probably correct.
He had a few more questions on it:
- Why a copper case?
- Why are the input terminals red and black; they're both the same?
- Why an inner core of carbon block and an outer core of carbon powder.
- Why no markings of any kind? (could be a paper label which came off at
Somebody suggested the copper case was possibly an RF shield, which sounds
good except it's not grounded to anything!
Shielding -- keep the signal inside -- or keep an external
signal from getting in.
Commonly supplied in colored pairs, as they are commonly used
for speaker outputs on amplifiers. You can buy them all in one color,
or in mounted pairs or whatever, but the most readily available are in
red/black pairs. Aside from the red and black, in good quality ones,
such as those by Greyhill, I also have some green and blue ones.
Here is what Graywhill's binding posts look like:
note that tehy come either with individual panel insulators, or ones
which hold two at the standard 3/4" spacing. (For that matter, I know
that they at least once had triangular patterns of three as well.
Downloading the data sheet, I no longer see the triangular three post
base insulator. But these were perhaps twenty years ago. :-)
From other makers, I have also seen yellow and white ones.
Others, once made by General Radio, were available in three
colors -- red, black, and bare metal. The latter was used as a ground,
the black was often right next to it with a sliding link to allow
grounding it or not at need, and the third was red, which was the hot
But these look like the poor quality ones which were once sold
by Radio Shack -- and those would have been sold with the assumption
that they would be used as speaker terminals, thus the red and black
pairs. Radio Shack also offers (at least on their web site) some better
quality ones as well.
I just went searching on Radio Shack's web page, and found this
These look very much like the ones which were in the device under
discussion. They are sold in packs of two pairs -- two red and two black.
Perhaps to even out clumping? Was there no carbon powder in
contact with the rods?
Note that carbon granule microphones in use tended to clump, and
had to be bumped to break up the clumps. Think of the old telephones
(which used carbon granule microphones), and how occasionally they would
produce weak sound. If you bumped the microphone end of the handset
against a table it would break up the clumping and improve the sound
Could be -- or if it was unique -- or one of only a few, the
distinctive color pattern could explain what it was to those who were
presumed to need to know. :-)
A complete copper shield does not have to be grounded to block
RF. It can be advantageous to ground it if you want to control buildup
of static voltages, of course.
Or -- it could be that there was a connection from the black
binding post to the copper case -- which would serve as the requested
reason for the two colors.
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