The morning news. [volume] (Savannah, Ga.) 1887-1900, 1897-12-09

end exactly balances the pull of The motor
at the other end; another electrical con-
tact preserves this counterpoise. The po-
siuon of the motor-moved end Of the
spring denotes the tension or resistance OF
the model; and an arm reaching up to a
cylinder carrying a sheet of paper traces
with pen record of this resistance and
its variations. This cylinder, before which
one of the operators sits, revolves at a
fixed ratio to the advance of the carriage.
other pens register any change of trim,
J. e., settling by the bow or the stern,
at regular periods, and the actual distance
and position of the carriage at every in
terval of the run. These latter elements
are checked electrically from the track
and must be positive. and, by the combi-
nation with the time record determine
the actual speed of the carriage at any
point in its run, The result is digram
OF simultaneous records from which ev-
erything can be read and checked with
ease. The springs used will necessarily
vary in strength with the speed and
character Of the model; and the standing
weighing apparatus will he used to stand
alone each one before trials
Every conceivable precaution will he
taken to insure absolute accuracy in the
tests, and a careful record of each ex-
pertinent will be tabulated and filed away
Tor ready reference. In the matter of de-
tails and the method of applying the dy-
parted entirely from all previous prac-
tees, with the promise of records free
from that Jumpiness ana vibration COM
mon TO other model tank registers.
IN addition to these more simple expert
ments, arrangements will be provided for
testing the functions or qualities of the
models; the effects of propellers of Vari-
Gus sorts and at different speeds, and their
relations to the form of the hull about
the stern where the water runs in to the
screws; and also to tell what proportionate
part Of the total resistance of the model
is due to friction of the underwater sur
face. what ~ wave resistance and what
to eddies.
All Of these things must be taken into
consideration in determining the best form
for ship and the corresponding economi-
cal speed for that form; ana from this,
some modest notion may be got of what
the naval architect has TO provide for
and consider In the absence of a tank.
he must make the most of the known per-
formances of other ships and approximate
the possibilities of his intended craft as
best his judgment can. Pretty guess work
and some wonderfully clever forethought
alone are the basis upon which our own
successful ships have been planned so far,
and one naturally wonders what might
not have been accomplished had we had
these absolute, practical facilities.
The high speed at which il may he need
ful to run the carriage-twnety knots, or
twenty three mics an hour-necessitates
some special and reliable arrangement at
the end of the run for br nging the carriage
to a halt without undue shock TO the heavy
mass in notion This is to be accomplish
ed by huge friction brake carefully grad
uated i'm its pressure by hydraulic Cylind-
ers. and operating uniformly on each side
of the carriage When this brake is in
operation it will be possible to bring the
carriage to stop from full speed within
twenty feet A supplementary or emer-
gency brake, in the shape of an immense
hydraulic cylinder, is automatically thrown
into gear upon the failure Of the friction
brakes, and will be absolute in case of ac-
cident
The models to be experimental upon will
be nearly as possible of uniform
length of twenty feet as an oven scale pro-
portionate to the full-sized craft will al
low. For instance, a vessel So feet long
will have model on an eighth scale, that
is, 1872 feet long, while "a craft 1888 feet
long will have a model on nineteen
scale or pol feet long. They will be of
pine wood, accurately cut by q special ma
chine from the lines of the proposed YES
sell and then carefully measured and
checked before being launched into the
the basin. They will then be prepared in
the balancing basin prior to starting and
nicely baliaSted so as to represent
accurately the intended craft when she is
ready for her trial
In order to lessen the chance of distrub-
ing draughts the walls Of the building will
be without windows, light and air coming
in through the glazed skylight above The
steel trussed roof is both unique and light
and does away entirely with an obslructing
support against the walls Of the building.
and leaves an unbroken run for a gallery
on each side where the models may be
conveniently stored after trial and space
also for a foot path from which photo
graphs of the modes under way may be
taken and other observations made The
entire structure inside will be painted
white, and besides providing a light and
convenient building for the work In hand.
Will present an attractive appearance
The Advantages to be gained by expert
menting with such apparatus both from
scientific and a practical point of view,
are clear. 1t is easy to say that because
a certain vessel steamed so fast that an
other of similar form and even power will
go at the same speed under like conditions.
or it Is possible to approximate closely
even when departing to some extent from
a strict parallel by reasoning from past
experiences.
Undoubtedly many fine ships have been
designed and built, but the fact remains
that the speed and coal consumption in
many cases have varied widely from that
expected. Perhaps, in some cases, the ac-
tual results could not have been foreseen
or provided against in any event, but it
is certain that many failures could have
been prevented had the designs first been
tested and proved or dlsapproved by mod
els in the manner proposed.
1t is in connection with radical changes
of form and conditions as to power, draft
Of water, etc, and with designs wherein
the limits are closely drawn that the value
of the basin becomes paramount Ten
years ago any one suggesting thirty knots
as being possible of attainment with a self
propelled vessel would have been consid-
cred visionary. To-day contracts are be-
ing made for vessels with a guarantee Of
even higher speed, ana who can say what
is to be the possible limit?
For strictly commercial purposes, how
ever where the desiderata are maximum
speed with large carrying capacity on O.
moderate expenditure of power and a light
consumption of coal, the value Of model
trials is Of prime Importance, as they
would also be where the attainment Of
exceptionally high speed were the prere-
qusite.
1t is hard to compass the possible ad-
vantages and the great national import
ance of such tank and its facilities. and