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Re: [rete] Models (fwd)



I know that in the past there have been conversations about models we use,
in particular the fluid model for electric current. I thought some of you
might find this interesting.

cheers,

joe

Joseph J. Bellina, Jr. 574-284-4662
Associate Professor of Physics
Saint Mary's College
Notre Dame, IN 46556

---------- Forwarded message ----------
Date: Mon, 08 Sep 2003 13:48:02 +0100
From: Roland Wittje <roland.wittje@phys.ntnu.no>
Reply-To: rete@maillist.ox.ac.uk
To: rete@maillist.ox.ac.uk
Subject: Re: [rete] Models

Dear Retians, dear Paolo,

I had posted this reply to Paolos request about ten days ago. It seems
like it has never been distributed, so I am trying again:

Apart from Bjerknes' hydromechanical analogies of electricity and
magnetism, which I had demonstrated on the Scientific Instrument Symposium
in Stockholm in 2001, I also have a simple hydromechanical model of a
Wheatstone bridge in my collection. The model consists of a tin sheet
container and a system of channels made of lead, for the fluid, most
probably whater, to run into a tin trunk. The model was most probably made
locally at the instrument workshop of the physics department of the
Norwegian Institute of Technology, Trondheim, between 1910 and 1915. I
have put up a photo of it being set up for lecture demonstrations in 1915
on my internet page:

http://www.phys.ntnu.no/~rolandw/wheatstone.jpg

The model is still in the collection, but partly damaged.

Several of the instruments of Carl Anton Bjerknes' research program on the
hydromechanical analogies of electricity and magnetism are preserved at
the Norwegian Museum of Science and Industry in Oslo. I also found pieces
of the instrument bought by Philip Lenard in 1909 on an attic of the
University of Heidelberg.

I hope that more of these mechanical and hydromechanical models of
electricity and magnetism have survived, adding streamline models and
hydromechanical models of to-phase and three-phase electric motors to the
list of devices that existed.

Best wishes

Roland

-------------------------------------------

Roland Wittje
Dep. of Physics
NTNU
7491 Trondheim
Norway

Tel. +47-73-593356
Fax +47-73-597710
E-mail: Rolandw@phys.ntnu.no

On Mon, 18 Aug 2003, Paolo Brenni wrote:

Dear Retians,
if you are not still on vacation I have a question for you....
I am looking for surviving mechanical or hydraulic models used for
illustrating electrical phenomena, theories as well as the working of
electrical apparatus (Wheatstone bridge, Leyden jar, etc).
Of couse I know of the famous Maxwell's, mechanical model of electrical
induction, but do the models of Lodge or Fitzgerald survives?
Thanks
Yours Paolo Brenni



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