National Republican., 1883-09-08

timatCd that
stances Of the
wave and sub
stress on the
coed three tons
Iraro completely
.tional protection
'ad, false rudder-
utal shield or Hat
htiug hand VIII ell
engine Will be
fiat TO which com
Q by telegraph from
so be a hand steering
*, and n steam steer
house on the forward
two bridges one for
-, extending over the
"A this bridge roOmy
Iably an armored pilot
The second bridge will
fturrets.
be ark-rigged the area of
80 square feet, or above
II pOwor. 1t is intended
uXliary, as tho coal supply
,ly power for long voyages
,. Tho normal coal supply
unkcr capacity is $40 tons,
ditional can be safely and
the berth deck. Thus, with
ply OF about 1,24O tons, the
sam 3OOOmiles at 10 knots and
lO-ll knots per hour.
will be ventilated by an exhaust
ar to that so successfully cm-
o United States steamer Rich
large blowers situated on the
draw air through large ducts ex-
e and aft, and with branches to all
.ces ans store rooms and deliver
leading to the open air. A separate
used for the engine and boiler COM
is. Pipes are fitted leading from the
to supply fresh air TO the coal bun
i'd another system, delivering into the
casing, providing an exhaust for gases
may escape from the semi-bituminous
be carried.
chin ery.-The Chicago will have twin
vs., actuated by two pairs of two-cylinder
pound overhead beam engines, shown in
o 8. Each engine, with its independent
siliary machinery, will be placed in sep
lte water tight compartment % feet long
y inclosod by the protective deck which il
Ainches above the water line amidships,
dVing a height in' clear between the inner
Jottom and the unaersido of beams Of 15 feet
inches.
The high and low pressure cylinders will
be located side by side, with axes vertical,
eight feet apart and respectively 2 feet 1
inch and 8 feet inches from the midship
line, tho cylinders of the forward engine
being placed on the port side. Their dameters
will be 40 and 70 inches, and their piston
stroke Sc inches.
Arguments in favor of beam engines and
the use of the twin screw are set forth at
some length
The weight Of the machinery forming such
an important factor in the design, the ques-
tion of coal has demanded attention, and argu-
ments in favor of soft coal are given The
weight saved in the weight of tho machinery
of the Chicago by designing on the basis of
soft coal amounts to more than the whole
weight Of the armament, or to two days coal
supply at full power, or, other things being
the same, il would have been impossible to
carry protective deck.
The type Of boiler intended for the Chicago
is new to the naval service, but is in success
fu operation in merchant steamers. There
will be fourteen horizontal return.tubular
boilers designed TO carry working pressure
of 100 lbs. per square inch and constructed of
steel which must conform to the tests or
steel for cruisers" prescribed by the naval
advisory board. They will be contained in
two separate watcrtight compartments. The
hro rooms run fore aud aft and are to be IL
feet wide, except between the two forward
boilers, which are canted inbUard. There
are to be two fixed smokepipes, each connect
ing with an up-takc common to the boilers Of
each compartment. Each boiler will bo feet
in external diameter it, 10 in in length on
the bottom and set inclming downward from
front to back, over single furnace below the
shell, being supported by girders of boiler
plato lined with fire brick
The tiro-rooms will he made air tight and
will be fitted with two large blowers each,
which it is expected will he capable of main
tanning pressure of about an inch of water
above the atmosphere, BY this means the
rate OF combustion eau be readily doubled
when great speed is required for a short
period.
The advantage claimed for these boilers
over cylindrical marine boilers of ordinary
construction having the same amount Of CRATE
and heating surface is less space occupied
in the vessel and they are particularly we'll
fitted for hlgh plcssures.
The question Of the speed of these cruisers
is md int
est; but, on tho other hand, an exceedingly
delicate one to consider Tho most--or, we
may say, the only-satisiactory method of
approaching 1t is by comparison with reliable
trials and careful experiments upon similar
vessels. The absence OF any such data in the
navy makes IT necessary 10 be very cautious.
Ample power has been provided to obtain the
designed speed, aud If the machinery proves
efficient and the screws suitable, il win not
be surprise ii tho CHICAGO makes nearly
sixteen knots on the measured mile. When
these vessels are finished and the elaborate
trials made oftneir Speed and the efficiency
OF thor paChinery upon measured dis
NTe, GAjsh is now the recognized standard
ii performance, th0n il will be possible 10
more carefully analyZe the design, and, by
giving to one part and taking from another,
endeayor TO improve the vessels which may
follow. With this view the contracts have
been carefully drawn, making il necessary TO
weigh each piece OF material and every arti-
hull and machinery. In case of the Chicago
othe contractors guarantee, undor penalty.
that the weight of the machinery shall not
exceed 937 tons.
SINGLE SCREW STEAM CRUISERS BOSTON AND
ATLANTA.
Length between perpendicuars..s.. 27e f.
Length water hne,........'...... 276
Length over all,....s......"..,s...', 2eS
Depth from cardboard stfake 10 under
side of supefstructurs deCk,.,,...-, 81
Height Of main deck port Sill nom
load water lne,.....,,..,.......,, IL
Free board NJ eNtremites Of SUPER
structure. ....s.'s,..s.'''''s..'.,.,,s
Breadth-eNtreme. me......,.'.,...,s..,t ~
DIaught at load water line-mean"., 16 n. 10 in
Displacement Of water line. ..-........ 5000 tons.
Area OF plain sRil,.".,....."...,.., TO- 400 10. H.
Complement Of men.......,..,......, $50
Battery, four s-ineh aud six 6'ineh
b.. r.
Indicated horse poWer"",""...-. $500