The record-union. [volume] (Sacramento, Calif.) 1891-1903, 1899-11-13

pany of soldiers. As you are doubtless
aware, the Calling gun was the earliest
of these These, too, have been devel-
oped during the intervening years UNI
til it would seem that finality has all
most been reached in the Maxim gun,
where when once started it continues
to discharge itself by the effect of it's
own recoil, until the old metaphor,
iron and leaden hail." becomes a sim
pie matter of fact The Maxim gun
will fire 600 shots a minute from cali
Der of G. 10 inches or less.
We come now to the machinery of the
modern vessel, and trust that you will
pardon me if 1 go into greater detail
here, because this is my own special
field, and one where it has been my lot
to have been intimately associated with
the construction of our new fleet Here,
more than almost anywhere else in the
war vessel, the constant demand has
been for greater power on less weight,
and at the same time the demand has
also been for thoroughly reliable ma
chinery that would also be economical.
FURNISHING POWER FOR WAR
SHIPS.
Progress has been so rapid that it
sometimes seems that we hardly have
| time to get out a design as nearly per-
feet as possible and see it thoroughly
tested in service before Improvements
have been suggested that render what
appeared so perfect relative obsolete
Shortly before I became Engineer
Chief of. the Navy, forced draught
had been reintroduced after many
years Of disuse, which at once gave an
enormous increase of boiler power with
a. very slight increase of weight due to
the burning of much larger amount of
coal on a given crate surface. The
shell boiler was developed until it's de-
sign seemed nearly perfect, but we were
confronted with the problem of getting
plates sufficiently thick to withstand
| the increasing steam pressure in the
large boilers and still be able to prop
erly work the plates in our shops. The
weight of these boilers was always very
great for the power developed, and in
the large sizes which they had reached
the utmost skill was necessary for their
proper care and maintenance Shortly
before the time had come when further
progress with the shell boiler seemed
impossible, the water tube boiler was
us the necessary solution of the prob
lem. and it now seems quite certain
that, for some time to come, at least,
the boiler problem has resolved itself
into a determination of the best form of
water tube boiler, inasmuch as we are
now sure that we can construct boil
ers which wilfswithstand any pressures
that are likely tovbe used and which
are satisfactory In every other respect
These boilers offer almost absolute
safety against disastrous explosion, af-
ford a great reduction in weight, and
are built to withstand comparatively
rough treatment as far as heat is con-
cerned, thus giving freedom from such
troubles as leaky tubes and leaky
seams to which large shell boilers are
very liable.
/ The demand for reduction of weights
in the engines has been met by the use
of stronger materials, and also their
disposition in shapes where a given
weight of material offers the greatest
resistance. We thus have steel cast
ings to replace cast iron; hollow forg-
ings of oil tempered steel, and the use
of bronzes Of double the strength of the
older compositions. Besides the greater
strength of the materials, just as i'm
portant an item is their much greater
| reliability. Our manufacturers to-day
can furnish us with forgings where we
know that the results obtained on test
pieces will be absolutely true of every
part of the whole mass.
/ Weights have also been. greatly re-
duced by using engines which run at
much greater speed than formerly OBJ
tanned. This seems a sufficiently simple
matter, and yet it was not possible un-
til the improvement came in materials,
combined with an accurate scientific
knowledge Of some Of the questions con-
fronting the marine engineer which had
formerly been solved almost by rule
Of thumb. This is nota bly, the case with
propeller design, for it was the mis-
taken notions on this point that really
held down the engine speeds. mas
much as the whole Office of the motive
machinery is to turn the propellers, it
might seem that it would be necessary
to design the propeller first and make
everything else to suit it, but FORUM
ately, now that we have accurate scien-
tific knowledge of the conditions gov
erning propeller design, we know that
the piopelei can De arranged TO suit
almost any speeds found desirable for
1he engines, and this enables us to
choose engine speeds which will give
us both lighter and more economical
ones than were possible in olden days.
problem in the design of engines for
war vessels which is of consid era BILE
difficulty, and the solution of which is
not yet thoroughly satisfactory, is that
of securing economical results at ordi-
nary cruising speeds, with the capacity
for the power necessary at maximum
speeds. AS you are doubtless aware,
the power necessary to drive 4 vessel
varies approximately as the cube of the
speed, so that it, as is ordinarily the
case, the cruising speed is about half
the maximum, the power to be devel-
oped is one-eighth or less of the maxi
mum. AS was very cleverly expressed
by one OF my former assistants pro
lessor Hollis) some years ago, the prob
lem is like that of having a beast of
burden whose maximum power will be
that of an elephant, but whose appetite
is so adjustable that he could be eco
nomically used for work which could
be performed by donkey. You well
know that an elephant would eat about
the same whatever work he was doing.
and while this is not exactly true of
steam engine, it nevertheless is true
that its economy when worked ut DOW
ers which are such a small percentage
OF the maximum is very much reduced.
In some of our ships we have tried to
solve this by arranging two Satc of q,