The large water surface afforded for escape
of steam secures almost entire freedom from priming, without the
incumbrance of steam domes; and the large combustion chamber allows of
the thorough combustion of the gases before their passage through the
tubes. The locomotive type of boiler has lately occupied the writer's
attention, with a view to its more definite introduction into marine
work. The difficulties, however, which lie in the way of applying it to
steamers going long voyages are very great. The principal difficulty
lies in the necessity of burning a large quantity of fuel in a very
limited space and time. This can only be done either by direct pressure
or exhaust action applied at the furnace. In other words, we must either
exhaust the funnel, which will absorb a large amount of power, but would
be comparatively easy of application; or our stokers, as is the case
with our miners, must work under a pressure of air.
STEEL BOILERS.
The writer stated that his experience in the manufacture and working of
steel boilers was satisfactory. Many steel boilers of sizes varying from
six feet diameter to fourteen feet six inches diameter have left the
works at St. Peter's since 1877, when the first was made; and in no
case has there been a failure of a plate after being put into a boiler,
either in the process of manufacture or in working at sea.
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