On Tue, 10 Feb 2004 22:11:15 -0800 (PST), in a place far, far away,
Pat Flannery made the phosphor on my monitor glow
in such a way as to indicate that:

http://www.egr.msu.edu/~lira/supp/steam/
In this type of engine, the cylinder had to have enough strength to
resist _implosion_ as the piston was sucked into it.

On Earth the difference between a vacuum and the pressure of the
atmosphere is only around 14.7 PSI at sea level, so you can't generate
much power with one of these things without making it very large;

You mean like a Newcomen engine? The one that kicked off the
Industrial Revolution?

http://technology.niagarac.on.ca/peo...e/newcomen.htm

It did, admittedly, have a poor power/weight ratio...