"lightning machine" at Chicago's Museum of Science & Industry? (fwd)

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Original poster: Steven Roys <sroys@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Thu, 1 Jun 2006 13:24:14 -0600
From: Gomez Addams <gomez@xxxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>, Tesla list <tesla@xxxxxxxxxx>
Subject: "lightning machine" at Chicago's Museum of Science & Industry?

This may have been asked on one of these lists before.  I may have  
even asked it myself a few years ago, because it's something I've  
been interested in for a long time, but if I ever did get an answer  
here, I didn't put it where I could find it again.  If I'm repeating  
myself, I apologize for my absent-mindedness.

By the way, this isn't really Tesla coil related, but it's close  
enough it ought to interest many on the TC list, and I figure someone  
else my age or older may know about it.

So: in the 1970s, the Chicago Museum of Science and Industry had  
something which my high school science teacher called a "Lightning  
Machine".  We took a field trip there (from Peoria) but to my dismay,  
they had shut it down only a few months before our visit.  According  
to the guide I talked to, they had found a hole in the ground cable  
which lead down from the second floor and into an elaborate ground  
system in the basement, and for that and other reasons (perhaps it  
had other problems) the powers that be had elected to not resume  
operating it.

I _think_ it was a Cockroft-Walton generator, because I never saw any  
spark gaps.  But knowing what I know now, it would make more sense  
that it was a Marx-type impulse generator.  At the time, I didn't  
know enough about such things to tell the difference by looking at it.

I have a vague memory that someone once told me it had been built for  
a World's Fair, perhaps the 1893 Columbian Exhibition.

What I DO know is that it looked very old, even in the 70's.  There  
was a large power transformer off to one side which had two glass  
mercury vapor rectifiers on top of it - pictures posted on the  
outside of the safety enclosure showed them glowing blue when it was  
running.  The structure itself was all black and polished brass  
parts.  There were several large (perhaps 12"x12"x24") black boxes  
mounted on the horizontal members.  I didn't see any spark gaps  
anywhere, but perhaps they were inside enclosures, like the PolyTron  
gaps that Hipotronics and Ferranti have used.  There was a beautiful  
brass railing around the entire machine just inside the safety  
enclosure (a wall with windows) at roughly head height.  The output  
of the machine terminated in (I think, my memory is hazy) two large  
brass or copper balls mounted on very large diameter copper or brass  
tubing, pipes, or rods.  IIRC, they were about 36" to 48" apart and  
vertical.  I believe the bottom one was connected to the various  
ground straps on the floor, including the safety railing, which would  
make sense.

The controls inside the phone-booth sized operator's booth were  
likewise antiquated, with projecting surface-mounted meters and old- 
fashioned hand-wheels.  The whole installation exuded hand-made  
craftsmanship of the sort you saw around the turn of the century.

Other pictures showed how they had blasted short (3 feet or so)  
sections of heavy lumber (telephone pole) into kindling with the  
discharge.

I have made many internet searches and never found _anything_ that  
references this machine.  Over the years, I've also made a few calls  
to the museum.  They always tell me I need to speak to the museum's  
chief historian who would know more, and every time I've been given a  
different name, and every time that person isn't in the office that day.

I would like to know ANYTHING solid that anyone knows about this  
machine.  What type it was (Marx or C-W), and anything you know about  
who built it, and when, what became of it after they shut it down,  
and so on.  Even hearing from someone else who has laid eyes on it  
would help reassure me that I didn't imagine it...

sincerely,
  - Bill "Gomez" Lemieux,
	Denver, Colorado, USA

..................................................
"The last 29 days of the month are the hardest."
                                    - Nikola Tesla