On Mon, 25 Jul 2011 02:53:44 -0700, Andy Dingley wrote:

On Jul 25, 6:27Â*am, harry wrote:

No-one in their right mind is going to lose sight of the water level.

A wise idea - mostly because it's very hard to tell if a gauge glass is
full of water or steam, once you've lost sight of the level - especially
on the LMS, where the gauge cocks were linked to a single handle, so you
couldn't blow one at a time.

Of course, in the earlies (or, indeed, up until the 1860s in many places)
it was a bit harder, as there weren't gauge glasses. Recommended procedure,
I have read, was to tap on the boiler side with a mallet (or similar) to
check whether it 'rang' at a given level. If it did, then that bit was above
water (the same method was used for whisky stills until well on in the
19th century - no reason for introducing that except it's a nice factoid :-)

With the small, domeless boilers of early years, the surging inherent in
primitive locomotives, the rocking and swaying inevitable on short rails
(3'ish, in most cases under early locomotives) and the horrible prospects
if a flue tube became uncovered for any length of time, priming must have
been near-universal on the pioneer locomotives, at least at the start of
a run (when there must have been a severe temptation to over-fill the
boiler rather than risk getting stuck away from any chance of refill/
suffering feed pump failure).

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