=A Glass Water Gauge= is a device attached to a boiler to show the
level of water in the boiler. It consists of a glass tube ten or
twelve inches long, with an angle valve attached at each end. The
lower valve enters the boiler below the water line, the top valve
enters the boiler above the water line in the steam space. The ends of
the glass are made steam and water tight by means of rubber gaskets and
stuffing boxes. As water will seek its own level, the height of water
in the boiler will show a corresponding height in the glass, and the
engineer at a glance knows just how high the water in the boiler is
above the flues and crown sheet.
[Illustration: Lunkenheimer Water Gauge.]