The Pacific commercial advertiser., 1900-12-28

water into steam as would those of !
the old type, thus permitting a great
reduction in the weight of boilers re-
quired to produce the necessary
amount of steam.
In order to feed these boilers under
the present system 1t would be neces-
sary TO have small army of men, but
recent success which has attended the
experiments with mechanical stokers
has caused the Vulcan people to look
into this matter closely. 1t has made
IT certainty that this vessel, when
constructed. will have her furnaces
fed with coal by machinery instead of
by hand. which will give additional
space for coal, besides saving a
great amount of room necessary for
large fire room force
Coal will be brought from bunkers
TO stokers automatically by machinery
and few men will be able to keep
watch on all the boilers. The en-
gines of this steamship have presented
most difficult problem.
They will have three shafts, each
with separate engine In order to
get sufficient power these engines will
indicate about $4,000 horse power
apiece. Under the present system of
heavy. slow moving engines. making
seventy or eighty revolutions a min
ute IT would be impossible to develop
this horse power within the space al
lowed for them in the new vessel
| Ii Is proposed to deliver the steam
TO the engine at a pressure of 27O
pounds TO the square inch. Steam of
this pressure can be made extremely
dry.
The cylinders will be considerably
smaller than those used with the pres
ent type of engines. and will be more
numerous. The steam will go to the
condensers, as at present. at practic-
ally atmospheric pressure. The en-
gine. instead of making eighty revolu-
tions. will probably make 200 per
minute
The only limit to the speed of en-
gines Is the tensile strength of ma
terial used in the moving parts. The
papers recently have contained ac-
counts of the bursting of fy-wheels on
engines. This was of course, due en-
tirely to the effect of centrifugal force.
The metal Is not strong enough to
hold together when revolving above a
certain rate of speed
IL Is known that some entirely new
compositions of metal will be used In
the moving parts of the engines OF
this new ship. Connecting and piston
} rods and such points will be light
enough to allow of running at high
speed as the new composition will
render them sufficiently strong to Dc
the work required of them, Withstand
ing the necessary amount OF centrifu
! gal force developed.
|
; er on the engines IL II necessary I.
| use that power in such way as tC
; give required speed to the vessel. A
: present there is no type OF propelle
4 in use which will develop sufficien
= speed In three propellers. allowing
Z one on each shaft
r The Vulcan people have accordingl,
= decided to adopt the hollow archie;
q stern. which characterizes so many o
the torpedo boats built by Yarroy
e and Thorneycroft. In addition to usini
a this hollow arched chamber unde
: the stern of the ship IL has been de
e cided to place two propellers on eac
n shaft, making six in all. The objec
n tion to this plan heretofore has al
{ ways been that the forward propelle
e on the same shaft disturbed the waite
i so much that the after propeller di
e not work in solid water and wa
u therefore doing but little good.
This difficulty has been remedied
l. a large extent, and in fact, almost er
n tirely obviated by some OF the Germa
n and English builders in more recer
10 types OF light draught gunboats bui
ss for river service. The water when
10 strikes the forward propeller is whir
n, ing and broken. II is to be, howeve
Of diverted or compressed by blades {
he per diagram, which deliver il to III
n second propeller on the same shaft
III practically as solid condition ;
n. when used by the first propeller.
e. or course there Is a certain amour
ne of friction on each OF these blade
re but allowing for this friction it h
OF been demonstrated that the secor
ny propeller will do at least three-fourtl
We as much work as the first one, th1
RS almost doubling the power of ea'
vo shaft
o. The enormous length of the ne
oh Continued on Page