The herald. [microfilm reel] (Los Angeles [Calif.]) 1893-1900, 1897-07-25

in 1855. when Sir Henry Bessemer per-
fected his method of producing steel by
a process which at one stroke reduced
the cost per ton from so to 910; since
then II has been reduced to 95. Bessemer
was endeavoring to produce stronger
weapon OF war for Napoleon III, when he
discovered that jets OF air forced into
vessel Ga "converter") filled with molten
iron. sufficed to keep 1t in a boiling state,
because of the carbon in the iron being
consumed, and as it was only necessary
to remove this carbon to make the poor
est of iron reliable steel it was a glad
some sight to see 1t effervescing. Thus,
while the warrior spirits Of France and
Germany were pleased with gun made
of the superior metal, as with toy,
great era OF peaceful triumphs was in
augurated In Britain. AS we have said,
the cost was reduced to one-fifth OF
what it had been, and a great impetus
was given to engineering; now lO,OO0,oUo
tons are made each year by Bessemer's
method, although other processes with
like result have been introduced.
So long as dimensions Of engines, of
ships, or Of any structure were not great,
strength could be ensured by solidlty;
but now efficiency and economy demand
that the highest result must be got per
unit of weight. Thus chemist metal
lurgist and engineer have worked to give
q tensile strength of thirty to forty tons
on the square inch for the working parts
OF engines, and Notwithstanding that
some parts Of the biggest engines travel
at rate of speed equal to 1000 feet per
minute the number Of breakdowns is sur
prisingly few. By this greater strength
l., l. h. cd
by quite fifty per cent. apart alto
gether from the results Of the multiple
expansions Of steam consequent on high
pressures, admitting Of itself of areduc-
ton in the size of engines for given
power The boilers now used are made
of plates up to one and three-quarters
inches thick for 210 pounds pressure
This seems the limit; change must
come. In the old boiler the water to be
converted into steam and the steam are
within a cylindrical tank with fire tubes
through it, so that there is need for great
thickness In the outer plating of the tank
or boiler. Under the new system the
water is within tubes and the fire plays
around them, 30 that there is no heavy
outside shell or tank, and the quantity of
water is less The saving in weight is in
the case of this "watertube boiler"
about forty per cent. Moreover, steam
Is generated much more quickly. higher
pressures are possible, collapse does not
involve the same danger, and repairs are
more easily made.
AS a result of increased steam pres
sure, superior metals, and improved
tools, the weight Of machinery is only
two-thirds what it was sixty years ago.
Thus the engines OF the fret Cunarder,
Britannia, of S1a knots speed, weighed
about 10 tons, although the power was
only 74O. A torpedo boat destroyer to-
day has machinery which develops 4500
horse power, and they only weigh 100
tons. The result of 4112 horse power for
every ton of machinery got with 30-knot
torpedo craft is about the highest yet
attained. 1t is probable that this ma
chinery might not stand the wear and
tear of ocean steaming, but with some
sea-going cruisers twenty horse power
per ton Is got; with our fastest ocean
steamers fourteen horse power per ton,
and with the ordinary tramp steamer
seven horse power. This ali means
greater capacity for carrying a paying
load. Thus sixty years ago the load
carried was only 10 per cent of the total
weight driven by the machinery of
ship; today steamers are built of the
same speed whose paying load Is near
ly rs per cent of the total load.
The locomotive Of 1887 was only about
fifteen to nineteen feet long over all.
with a wagon for coal behind. The
"Dunalastair" is flfty-three feet four
inches including the tender. The steam
generating surface, which is meas
ure of strength is now three times
greater. The steam pressure has in
creased nearly fourfold, so that the
power has gone up tenfold. The
"Dunalstair," as she stands is ten feet
high from the ground, weighs thirty
six tons and can walk off comfortably
with 300 tons behind her. while the old
world locomotive painted as if to break
her heart while doing or'e-third of the
speed with a fourth of the load. This
change is magnificent; but some may
ask is it business? One answer is that
the quantity of coal used per unit OF
power or load is much less than 1t used
to be- and Is Sa tisfactorily small. 1t va
ries with the speed. but for thirty miles
an hour thirty five pounds per mile SUI
fees, and this. too. for the heavy cor
ridor train unexcelled in lereth. weigh,