On Sun, 17 Jul 2011 16:23:44 +0100, Charles Ellson wrote:

On Sat, 16 Jul 2011 23:28:13 -0700 (PDT), harry
wrote:

On Jul 16, 9:27Â*pm, Andy Dingley wrote:
On Jul 16, 7:07Â*pm, harry wrote:

On Jul 16, 10:24Â*am, Guy Gorton wrote:
No that is correct. They had huge pistons and very long strokes.

Early steam engines actually ran on
vacuum.http://en.wikipedia.org/wiki/Atmospheric_engine

FFS! Â*Don't believe _anything_ on Wikipedia!

The staem was used to flush air out of the cylinders.

Er no, the air was displaced by the steam being fed into the cylinder.
Get your intentions and consequences in the right order.

That's really nitpicking on the terminology. Displacing something by
admitting another fluid (or gas, or vapour) is often referred to as
"flushing"..

When it was
condensed (By a water jet) the piston was"sucked down"by the resultant
vacuum.
Hence "atmospheric."

So some a litte boy would

Que ?

There were various methods of operating valves automatically from a
fairly early stage, but most of them seem to have required coughing
up patent royalties. Provided someone cheap (or free..) could be
found to operate the valves manually, that was often a better deal
for the owner of the engine. A typical arrangement seems to have been
for the child of someone working elsewhere in the operation to to
the job, either for a /very/ small wage or as part of their father's
employment terms.
One such childhood valve-operator was George Stephenson.

By the early 1800s operation via strikers (pins on the rods of the engine
flipping the valve across) seems to have become the normal method of
operation, though presumably a few manually-operated engines would still
remain. In the locomotive context, valves operated by strikers can be
seen on the two surviving Wylam machines - and in operation on the
replica at Beamish:

http://www.youtube.com/watch?v=v_MLpJQswF4

Note that the valves would always need to be worked manually to start the
engine or after reversing it. This could be difficult, particulary on
a locomotive at night (Jem Stephenson was said to be the only man
who could reverse 'Locomotion' on his own at night, though Mike Satow
reckoned he could do it with the replica)

operate the valves manually. A big advance was automatic operation.


--
From the Model M of Andy Breen, speaking only for himself