The evening times., 1899-07-05

The special machinery and apparatus for
yard, which was completed late last year,
have now been installed and the Con-
struction Bureau expects to go ahead with
its tests of the models of warships and
battle craft in general. The value of such
an experimental basin had for many years
been appreciated by the officials of the
Construction Bureau, but it was long
time before they were able to convince
Congress that one should be installed at
the navy yard. Finally, about two years
ago, 100000 was appropriated for the pur-
pose and the Bureau began the work of
constructing the experimental tank.
The basin is located in the southeast
corner of the Washington navy yard. The
building is 500 feet long and about 80 feet
wide inside. The water surface of the
basin is slightly shorter than the building,
being about 470 feet long. The water sur
face is 43 feet wide, and the depth, from
top of the coping TO the bottom of the
basin, is IA feet inches. The basin is
larger than any other in existence.
small models of ships for the purpose Of
deducing the resistance of a full-siZed
ship from that of the model was demon
strated by the late William Froude, wko,
at his own expense, established tank for
such experimental work at Torquay, Eng
land, about 1870.
The English Admiralty subsequently
recognized the value of his work and as
h,,il lar yaf
basin at Haslar, near Portsmouth, which
is now in charge of R. E. Froude, son of
Mr.. William Froude. Other governments,
notably Italy and Russia, were induced 10
establish model basins, which were large
ly copies of Froude's basin.
The foreign tanks invariably use paraf-
fin for the construction Of models, and
generally make them from ten to fourteen
feet long. The climate OF Washington is
SO warm in the summer that il was found
impossible TO obtain parafin which would
retain its rig.dity. Moreover, it was the
desire of the Bureau of Construction and
Repair TO make the models as large as pos
sible, thus eliminating one source of mac
curacy in applying the model experiments
to full-siZed ships. For these reasons wood
was adopted as the material for the mod
els, and, after some difficulty, a satisfac-
tory varnish was found which rendered
the surface OF the wood, TO all intents and
purposes, water-tight. The standard
length of model used is twenty feet.
1t is impossible to avoid a certain varia-
tion of the temperature of the water in
the basin, but as ample heating facilities
are provided, it is not expected the varia-
tion during the year will be sufficient 10
necessitate correction in the results Of ex-
periments on this account.
The basin is filled from the water sys-
TEN of Washington and will hold 100000
gallons. Two electrical centrifugal pumps
are provided. the larger OF which will
empty the tank in about four hours. The
leakage Of the basin, which is very slight,
and the evaporation are made up with Al
tered water. In practice a small stream of
fresh-filtered water is kept running into
the basin all the time and the level main
tained whenever desired by an adjustable
overflow.
The building and tank were designed by
the Bureau of Construction and Repair,
as well as the machinery for making mod
els. Experiments are being made upon
tried for the purpose of accumulating data
which will be constantly needed during the
life of the tank. AS soon as preliminary
lines Of the new third-class cruisers au-
thoriZed al the last session of Congress are
completed. experiments will be made with
them in the tank, with a view to intro
ducing any improvements found desirable.