steam chamber, by annular troughs. At the top domed part of the boiler
are two annular chambers, the outer one being intended to receive the
water upon entry from the feed-pump, and to contain any sedimentary
deposit which may be formed. The water next passes, by the pipe, _a_,
in the figure, into the inner chamber, surrounding the end of the
uptake flue, whence it flows through the pipe, _b_, down into the
first of the annular troughs above mentioned, and afterward overflows
these troughs in succession until it reaches the bottom. Mr. Moy
claims to have secured by this means a boiler of quick steaming
capacity, together with a reduction in the weight of metal, and
considerable economy of fuel. By the arrangement of the water in a
number of shallow layers a large steaming surface is obtained, and
there is a good steam space rendered available round the troughs. The
water also enters at a point where it may abstract as much heat as
possible from the furnace gases before they escape; and by the
separation of the top domed chamber from the rest of the boiler the
operation of scaling and cleaning is facilitated. The arrangement is
also adapted to horizontal and multitubular boilers, to be fired with
solid, liquid, or gaseous fuel.

[Illustration: IMPROVED BOILER.]

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THE ELEVATED RAILWAYS OF NEW YORK.