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. The mode
of working is as follows: For shell plates, from five-eighths inch
to seven-eighths inch thick, to warm each to a dark red heat before
rolling, having previously drilled a few holes to template for bolting
the strakes together; the longitudinal seams are usually lap joints
treble riveted, requiring the corners to be thinned, which is done after
rolling. The furnace plates are generally welded two plates in length,
and flanged to form Adamson rings, and at the back end to meet the tube
plate; the back flame-box plates are flanged, also the tube plates and
front and back plates; and wherever work is put on to the plate it
is annealed before going into the place. The rivet holes are drilled
throughout. In the putting together the longitudinal seams of the
thicker plates of the shells, great care is always taken to set the
upper and under plates for the lap to their proper angle before they
are bolted together, a point generally overlooked by the practical
boilersmith.