On Jul 27, 12:15*pm, Andy Breen wrote:

The standard way for a very long time on stationary boilers was a wooden
float on the water level, linked through a wire or cord to the outside.

That would mean a small hole in the top of the boiler, then?

http://commons.wikimedia.org/wiki/Fi...nuff_Mills.jpg

From the left, level gauge with pulley for the wire, deadweight and
lever safety valve, stop valve and manhole.