The Locomotive - Lighthouse Survival Blog

116 THE LOCOMOTIVE. [August,
tion. The flue from the boilers is flanged outward and riveted to the stack, as shown
iu the cut. This stack is necessarily weakened by cutting out an opening equal in area
to its own cross-section, for the entrance of the products of combustion. It must be
braced by guys as explained in the first part of the present article.
Iron stacks are also erected somewhat after the plan shown in Fig. 1, but without
the long bolts there shown, the requisite stability being secured by guys. The -best
stacks of this kind have a brick stump high enough to
receive the flue from the boilers, and on the top of this
stump the iron stack rests. The retaining bolts are
omitted, and guys are provided in the manner explained
above. This form of stack is cheaper than that shown
in Fig. 1, and many prefer it on that account; but it
does not look so well.
Stacks should be so designed and constructed that
the opening in them comes directly in line with the
boiler flue, as shown in Fig. 5. This is not always pos-
sible, and local conditions may render it necessary to
make one or more bends in the flue. The straight flue is
much to be ])referred, however, as it oft'ers less obstruction
to the free flow of gases which is essential to a good
draft.
When used with boilers having a breeching front,
iron stacks are often riveted directly to the breeching,
Fig. 5. — Illustrating the Relation of the Flue to the Stack.
as shown in Fig. 6. When this is done the gases have a freer exit, even, that when the
stack is arranged as in Fig. 5; but care should be taken to have the bolts and other
parts of the breeching and boiler front strong enough to sustain the weight of the stack.
Stacks that are riveted directly to the breeching pass straight up through the roof of the
boiler-house, and it is not unusual, in such cases, to dispense with guys and brace the stack
by a sheet- iron sleeve secured to the boiler-house roof, if that be high enough to give
the stack sufficient stability.
For temporary use, iron stacks may be secured in a similar manner to the uptake of
a flush front or overhanging front boiler, as indicated in Fig. 7. We do not recommend