ISEN-ASTC-L is a service of the Association of Science-Technology Centers
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Hi,
 I agree with Ian. Years ago we installed an exhibit at the Boston
Museum of Science with two suck clear cylinders that were about 35 feet
long. This was to show dropping a feather in a vacuum. The wall
thickness was 1/2 inch. They worked fine.

I also agree with Ian about being careful with any pressure or vacuum
device to avoid undue mechanical stress.

John Bowditch
Ann Arbor Hands-On Museum

-----Original Message-----
From: Informal Science Education Network
[mailto:[log in to unmask]] On Behalf Of Ian Russell
Sent: Monday, October 23, 2006 9:00 AM
To: [log in to unmask]
Subject: Re: Clear cylinders and pulling a vacuum.

ISEN-ASTC-L is a service of the Association of Science-Technology
Centers
Incorporated, a worldwide network of science museums and related
institutions.
************************************************************************
*****

Here in the UK it is possible to buy long Perspex (=Plexiglass) tubes 
with 30cm diameter. I have successfully produced a high-vacuum 
exhibit using this material. Mine used only a short length of ~30cm 
tube, but a longer length should be equally resistant to external 
pressure. Be careful to avoid bending forces though. Even with thick 
walls, it is possible to see inside with perfect clarity because this 
material is very precisely formed and highly transparent.

There's a photo of my version here (scroll down to "Silence of 
space") http://www.interactives.co.uk/hands_rumbo.htm


[log in to unmask] * http://www.interactives.co.uk
*
Give people facts and you feed their minds for an hour.
Awaken curiosity and they feed their own minds for a lifetime.
*
Ian Russell 

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