346
EXPLANATION OF THE PLATES.
I
PLATE XVII.
Fig. 1. is a section of a steam vessel with its boiler in two parts ; the right part
is shown in a section across it through one fire-place F, and its flues. N, P; and
through the cross flue L of the other fire-place, and through the safety valve U
(art. 263.); showing the dampers O, R, and the passages of the flues to the
chimney. Of the left part the fire-door end is shown with the fire-doors D D, the
handles for clearing the clinkers B B, the doors for cleaning the flues at E E E,
and the gauge cocks G; also part of the chimney C, the steam pipe S, and a slide
valve V, to shut off the steam from the engine. There should be as much space
between the boiler and the sides of the vessel, as to admit a person to go round to
examine it. The floor under the boiler should be rendered as strong as possible,
and the boiler should rest on a plate of iron bedded on a layer of bricks or tiles
laid over the floor in cement; in this manner a thin plate of wrought iron ex
tending under the whole, being flexible, and brick a slow conductor of heat, is
more secure than a much thicker cast-iron plate.
Fig. 2. is a plan, showing the arrangement of the two fire-places F F, and their
flues. The fire-door is at D, the fire on the grate F, the clinkers fall at H, and
the smoke turns at L and returns along the flue N, rises at O, and goes back along
a flue P over N. The boilers should be strengthened by internal frames disposed
in triangles, and so as to afford supports for the flues.
Fig. 3. is a longitudinal section through the boiler, and one of the fire-places: 1 the
same letters refer to the same parts in all the figures; see art. 239—244.: for the
fire and flue surface, art. 204. ; for the capacity, art. 215—220.; for the area of
the chimney, art. 278.; for safety valves, art. 259—272.; for the strength of
boilers, art. 525.; and for the management of sea water, art. 565.
1 In this last figure there is scarcely sufficient space allowed for the action of the slide valve V.
