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Re: CROOKS TUBE



This demonstration is the "Momentum of Electron Paddlewheel". It is
the *working* version of the "Crooke's Radiometer" which is not
evacuated, and consequently goes the wrong way to demonstrate
electron momentum.

Closer inspection will likely reveal a very slight incline in the
rails. This means that the "upward rotation direction" is due to the
electron momentum transfer, while the return downward rotation is due
to the inertia of the rotating paddle bringing it back down the hill,
until the electron momentum takes over again.

Most likely, your version was made by Leybold in Germany. It is no
longer manufactured for export to USA. It is my understanding that
this is due to the production of x-rays!

If it stops working properly, you can get it repaired (re-evacuated)
by a local neon sign glassblower. You will unlikely be able to
convince a scientific glassblower to touch it since it is made of
"soft" glass, rather than Pyrex or quartz. Very few scientific
glassblowers will "allow" soft glass in their shops because of the
risk of mixing the two kinds of glass and blowing up a piece of
expensively manufactured "hard" glassware. Karl

I have just come across a fully functional piece of equipment that may
be some form of a Crooks Tube and I wonder if anyone can fill in any
details on its operation.

The tube is beautifully made in an evacuated glass tube in which there
are two circular electrodes. Between the electrodes are parallel glass
rails on which a paddle wheel is mounted in such a way as it can roll
back and forth between the electrodes very smoothly. The paddles are
apparently coated with one color or phosphorescent material on one side
and another color on the other side. The paddle wheel is situated so
that the upper half of the paddle wheel is on a line that would connect
the two electrodes.

When it is energized it is caused to rotate and moves, quite rapidly, to
one end of the parallel rails exhibiting bright colors as to goes.

One surprising observation is that, no matter how level we seem to get
the device, the paddle wheel maintains a movement of rotating back and
forth continuously between the electrodes. I am assume that this is
because of the accumulated rotational inertia but I wonder if there is
something I am missing.

When might such an instrument have been made? Are they still available
anywhere? It is truly a fine piece of workmanship. Anyone have more
information about this device?

David Abineri



--
David Abineri
dabineri@choice.net