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Re: Mystery Equipment



Dear Samantha,

Item A is an inertia demonstrator. A card is placed on top of the cup
and a marble sits on top of it. The spring (which is badly deformed) is
used to snap the card out of the way and the marble falls into the cup.
This apparatus is worth fixing by rebending the spring, and is an
enjoyable and very old demonstration.

Items C are two small induction coils that may be used to light up
Geissler or other discharge tubes.

Item E is a tangent galvanometer that is missing its compass. See my
article in The Physics Teacher 35, 423-426 (1997) on this and other
galvanometers for its operation. This one was very likely made by the
L.E. Knott Apparatus company of Boston, and is listed $2.20 in the 1916
catalogue. By connecting to the three binding posts, 5, 10 or 15 turns
in the coil could be put into use. This one is probably six inches in
diameter.

Item H is a rotator from the early part of the 20th century. You can
find uses for it in the web site referenced below.

The black object on the left-hand side of Item G is an Ampere's Law
stand made by the L.E. Knott Apparatus Company of Boston and listed at
$2.65 in the 1916 catalogue. The four small objects at the top are
compasses for observing the direction of the magnetic field lines, and
the cut-out in the base originally held a somewhat larger compass. The
two items in the right-hand picture are also Ampere's law stands, but in
this case either a small compass or iron filings are used on the shelf
to indicate the direction of the magnetic field.

Item I rather surprises me. The basic piece of apparatus is a single
helix mounted atop the stand. You can use it with an air core, or with
brass or iron rods passing through it. The coil with two sections is
usually called a helix with three poles. If you look carefully, I
suspect that the two halves of the helix were wound in opposite
directions, thus giving, for example, a north pole at both outer ends
and south poles at the center. Normally the two coils are closer
together, giving the effect of a continuous coil. This cost $3.50 in the
1888 catalogue of James W. Queen of Philadelphia, although other makers
sold almost identical apparatus.

Item J is a nice little resistance box made by the Chicago Apparatus
Company (perhaps under the Milvay brand) that sold for about $15 in
1925. It is most unusual to find one with all of the shorting plugs in
place.

Item K is a variation of the Magdeburg Hemisphere demonstration that
makes it clear that you do not need a volume of air that must be pumped
out from between the two hemispheres. All you need is a flat iron or
steel plate and a bit of grease to seal the joint against
irregularities. During the summers of 1984-86, when I was the principal
lecturer for the Harvard summer school course in physics, I had a
horizontal plate clamped rather firmly about seven feet from the ground,
put on the part that you have, pumped it out, and swung from it. And I
am not skinny!

And now for the reference. Last month I published a web site with
about 1500 pictures of 19th and early 20th century physics teaching
apparatus. There is a good deal of text explaining the pictures, a
number of references and many internal jumps. I worked on this for three
years, although I really began collecting information about thirty years
ago. You may find the site at

www2.Kenyon.edu/Depts/Physics/EarlyApparatus/

An alternative way to get to the site is to go to the Kenyon College
site at www.kenyon.edu, go to the physics department page, and look for
the link there.

Best Regards,

Tom Greenslade
Professor Emeritus of Physics
Kenyon College
Gambier, Ohio 43022



S M Ryan wrote:

Hello! I have a new job that came with a sizeable classroom and tons of storage space. I've been going through the storage space and have found things I can only guess at. I have them posted, and would welcome any help from more seasoned veterans of the Physics classroom in identifying them.

http://www.geocities.com/fizziksweb/mystery.html

Thanks!

Ms. Samantha Ryan
"I have no special talents. I am only passionately curious." - Albert Einstein

Physics Teacher for Shamokin Area Jr/Sr High, PA
Online Portfolio: http://www.geocities.com/s2ryan/

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