Hopkinsville Kentuckian. [volume] (Hopkinsville, Ky.) 1889-1918, 1902-04-25
4 roY ocEAN.
oae Constructed at Washington to TEST
Ships for the Navy.

Il Vne Son8NuCteQ az " as Alu t0n ~ Ac'l
Ships for the Navy.
A quarter of a century ago an Eng
lish naval constructor, DR. William
Froud5, performed a series 1t expert
ments with scale models designed to
predetermne the resistance Of ships
{ being built for the navy lie made
small models of the vessels TO be con-
structed. giving great care TO the
preservation Of the scale and these
| models he then towod through the
water under varying conditions, by
mechanism extremely sensitive TO
variation in the pull. The tension IN
each case was carefully recorded, and
conclusions drawn as to the lines most
favorable for speed. To verify his re-
suits a British man-of-war was lowed
by another vessel, and the actual pull
on the tow rope was carefully meas
ured and compared with the results
Of experiments made with a small
model The two sets Of answers we're
so nearly alike as to leave no doubt of
the practicability Of actual expert
ments with reduced scale models
At the Washington navy yard a
model basin for experiments Of this
kind has been constructed, at cost Of
100000.
Within a building designed to pro-
tect it from all disturbing conditions
of the atmosphere is a tank of pure,
fresh water, $40 feet long and 43 feet
wide, with a uniform depth Of II feet
Spanning this narrow sheet Of water
is a movable bridge, set upon steel
rails, which run parallel to the length
of the basin Heavily built. and fast
ened and braced SO rigidly as to avoid
all unnecessary vibration, the bridge
is provided with a wonderful motor.
which can drive it along he rails. r.
need be, at the rate Of 20 knots an
hour
The model ofthe proposed ship, cut
from soft pine, conforming as nearly
as possible to a uniform 20-loot
length, and ballasted with theutmost
care, is firmly fastened to an arm
which projects from below the cen
ter Of the bridge ortowing carriage, as
ii is called. On thecaTiage are placed
all the delicate dynamometrical mech
anisms which record the "pull" of the
model as it glides through the wafer
beneath the span of the bridge This
multiplied by the proper ratio must
establish accurately the power that
will be required to overcome theresist-
ance of the finished vessel.
Thanks to an almost fawless e &C.
trical development, the bridge moves
forward with an even motion, with
out trace Of the rattle and jounee Of
an electric car
Besides the motormen. there are
two persons on the carriage duringa an
experiment They watch the pens Of
The recording cylinder Of the dyna-
mometer. These pens, by means Of
electricity register the actual distance
traversed, together with the varying
pull Of the model as thespeed changes
When all is ready for an expert
ment. at the clang Of a gong the
bridge starts from the south toward
.he north end of the tank. while be-
leath it the 20-foot warship glides
evenly through the filtered water. As
HE run nears its end and The specta-
tors wonder how the great bridge
with its precious freight of insru-
ments is going oescape collision with
he wall ahead. two great hydraulic
brakes operate automatically and
bring The mass toa gentle stop with
mt a jar or quiver-Youth's Com
DanlOD.