Don,

You are getting into "chicken and egg" territory now. Without having done a
Google on it, I would say weight-lift steam pressure gauges came along well
before water column gauges. As an intuitive guess (aren't all guesses
intuitive) I presume a steam boiler with a proper weight-lift safety valve
would be self-regulating to such an extent that a pressure gauge would not
be absolutely necessary.

Bob Swinney
"Don Stauffer" wrote in message
...
Joseph Gwinn wrote:
In article ,
"Leo Lichtman" wrote:


"Robert Swinney" wrote: AFAIK, the earliest ones were mercury columns
or water columns. (clip)
^^^^^^^^^^^^^^^^^
Want to make yourself smile? Picture a water column attached to a steam
boiler at 150 psi.*
________________________
* Water column about 300 ft tall.


High-pressure steam only came (in the 1800s) after James Watt, who
abhored high-pressure steam because of the then considerable danger from
boiler explosions. It took a long time for steel quality and boiler
safety systems to mature enough that a 150 psi boiler was practical for
general use.


Even though Watt hated high pressure steam, Oliver Evens in US was a
proponent even before 1800, as were others around the world. Thus, from
previous answers, I see that there was a gap of five decades between the
development of high pressure steam and a decent gauge. Maybe that helps
explain the number of boiler explosions :-) What I was just reading
recently indicates pressures in 1820-1830 on western riverboats was about
30-40 psi, but someone (forgot who) had a 1850 psi system by around 1850.
Sure hope he had a gauge on those! Anyway, that is why my question, and
thanks for the answers, guys. Just what I was looking for. Now, how
early were safety valves. Seems to me I remember reading that they were
ealier, before 1800 by quite a bit. May well depend on what TYPE of
safety valve, however.