The Saint Paul globe. (St. Paul, Minn.) 1896-1905, 1897-08-16

iron sufficed to keep it in boiling
state, because of the carbon in tke
iron being consumed, and as it was
only necessary to remove this carbon
to make the poorest of iron reliable
steel, 1t was a gladstone sight to see
1t effervescing. Thus, while the war
rior spirits of France and Germany
were pleased with a gun made of the
superior metal, as with toy, great
era Of peaceful triumphs was inaugu-
rated in Britain AS we have said, the
cost was reduced to one-fffth what it
had been, and great impetus was
given to engineering; now 100000
tons are made each year by Bessemer's
method, although other processes with
q 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
solidity; but now efficiency and econ
omy demand that the highest result
must be got per unit Of weight Thus
chemist, metallurgist and engineer
have worked to give a tensile strength
Of thirty or forty tons on the square
inch for the working parts of engines.
of the biggest engines travel at a rate
of speed equal to 1000 feet per minute,
the number Of breakdowns is surpris-
ngly few. By this greater strength
the weight of engines has been reduc-
ed by quite so per cent, apart alto
gether from the results of the multiple
expansions CT steam consequent on
high pressures, admitting Of itself of a
reduction in the size of engines for a
given power. The boilers now used are
made of plates up to IL inches thick
for 21O 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
1t, so that there is need for great thick
ness in the outer plating of the tank
or boiler. Under the new system the
water is within tubes, and the fire
plays around them, so 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 water
tube boiler" about 40 per cent. More
over, 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
suTes. superior metal, and improved
tools, the weight of machinery is onlv
two-thirds what it was sixty wears
ago. Thus the engines of the first
Cunarderi Britannia, of 81 knots
speed, weighted about ITO tons, al
though the power was only 74O. A
torpedo boat destroyer today has ma.
chinery which developes $500 horse
power, and they only weigh 100 tons.
The result of 4f1a horse power, for
every ton Of machinery got with 30
knot torpedo craft is about the highest
yet attained. 1t is probable that this
machinery might not stand the wear
and tear of ocean steaming, but with
some sea-going cruisers 20 horsepower
per ton is got; with our fastest ocean
steamers IA horsepower per ton and
with the ordinary tramp steamer z
horsepower. This all means greater
capacity for carrying a paying load
Ihls sixty years ago, the load carried
was only 10 per cent Of the total
weight driven by the machinery Of the
snip; today steamers are built of the
same speed whose paying load is near
ty 70 per cent Of the total load
he locomotive Of 1857 was only about
10 to 19 feet long over all. with a
wagon for coal behind The "DunaI-
esteir is 30 feet inches including the
tender. The steam generating surface
winch Is measure of strength. is
now three times greater. The steam
pressure has increased nearly four
fold. so that the power has gone I'D