Solder the top of the dome in 1/8 inch below the end of the
tube, and burr the end over. The joint should be run again afterwards to
ensure its being tight.
[Illustration: FIG. 85.--Showing how to mark out strengthening patch
round steam dome hole.]
The positions of stays and gauges is shown in Fig. 83.
Chimney.--This should be an elbow of iron piping fitting the inside of
the flue closely, made up of a 9-inch and a 4-inch part. The last slips
into the end of the flue; the first may contain a coil for superheating the
steam.
A Multitubular Boiler.
[Illustration: FIG. 86.--Cross section of multitubular boiler.]
Figs. 86 and 87 are respectively end and side elevations of a multitubular
boiler having over 600 square inches of heating surface--most of it
contributed by the tubes--and intended for firing with solid fuel.
The boiler has a main water-drum, A, 5 inches in diameter and 18 inches
long, and two smaller water-drums, B and C, 2-1/2 by 18 inches, connected
by two series of tubes, G and H, each set comprising 20 tubes. The H tubes
are not exposed to the fire so directly as the G tubes, but as they enter
the main drum at a higher point, the circulation is improved by uniting A
to B and C at both ends by large 1-inch drawn tubes, F.
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