ries of experiments to see in what manner the steam generated was
separated from the water either in the drum or in its passage to the
drum. Glass peepholes were installed in each end of a drum in a boiler
of the marine design, at the point midway between that at which the
horizontal circulating tubes entered the drum and the drum baffle plate.
By holding a light at one of these peepholes the action in the drum was
clearly seen through the other. It was found that with the boiler
operated under three-quarter inch ashpit pressure, which, with the fuel
used would be equivalent to approximately 185 per cent of rating for
stationary boiler practice, that each tube was delivering with great
velocity a stream of solid water, which filled the tube for half its
cross sectional area. There was no spray or mist accompanying such
delivery, clearly indicating that the steam had entirely separated from
the water in its passage through the horizontal circulating tubes, which
in the boiler in question were but 50 inches long.

[Illustration: Northwest Station of the Commonwealth Edison Co.,
Chicago, Ill. This Installation Consists of 11,360 Horse Power of
Babcock & Wilcox Boilers and Superheaters, Equipped with Babcock &
Wilcox Chain Grate Stokers]

These experiments proved conclusively that the size of the steam drums
in the cross drum design has no appreciable effect in determining the
amount of liberating surface, and that sufficient liberating surface is
provided in the circulating tubes alone. If further proof of the ability
of this design of boiler to deliver dry steam is required, such proof is
perhaps best seen in the continued use of the Babcock & Wilcox marine
boiler, in which the cross drum is used exclusively, and with which
rates of evaporation are obtained far in excess of those secured in
ordinary practice.

Quick Steaming--The advantages of water-tube boilers as a class over
fire-tube boilers in ability to raise steam quickly have been indicated.

Due to the constant and thorough circulation resulting from the
sectional nature of the Babcock & Wilcox boiler, steam may be raised
more rapidly than in practically any other water-tube design.

In starting up a cold Babcock & Wilcox boiler with either coal or oil
fuel, where a proper furnace arrangement is supplied, steam may be
raised to a pressure of 200 pounds in less than half an hour. With a
Babcock & Wilcox boiler in a test where forced draft was available,
steam