New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1899-07-04
A BASIN FOR MODELS.
detrimental TOWING TANK AT THE
WASHINGTON NAVY YARD.
-,.,cr FOR AscERTAINING THE RESISTANCE OF
A PUBLISHED SHIP.

-..,nS+on July (speciaD-The value OF tow
,neriments upon small-scae models OF ships
o. the purpose of deducing the resistance OF
.,uszed ship from that OF the small model was
srronstrated by the late William Froude, who at
~. own expense started small tank for such
~rerlmental work at Torquay. England, about
,sao The English Admiralty subsequently, recog-
,,ad the value OF his work. and assisted him In II.
later building larger basin at Hasar, near Ports
Mouth which Is in charge OF r. Il. Froude,
son Of William Froude Other governments. nota-
INV Italy and Russia induced 10 establish
model basins which were largely copies Of Froudes
hos,n and one firm OF private builders-Denny
pros OF Dumbarton Scotland-were sufficiently en-
,srprising TO build a basin for their own
The Construction Bureau OF the Navy Depart
rnent has appreciated for many years the value OF
an experimental basin but It was for long time
unable 10 secure appropriation for the purpose.
Congress finally. about two years ago granted
s,0O 600 for this work The basin proper com
pfed the latter part OF last year. and the special
machinery and apparatus have just been COM
Melted and installed. after good deal Of delay
due indirectly 10 the with Spain.
The basin is located In the southeast corner OF
the Washington Navy Yard. The building is 800
feet long and about so feet wide. The water sur
face OF the basin is slightly shorter than the build
ing being about 40 feet long The deep portion IS
about 80 feet long. the south end. from which
runs begin. being shallow. The water surface is
AZ feet wide and the depth from top OF coping
10 the bottom Of the basin Is "A feet inches The
basin is materially larger than any other in ex-
istence The nature of the ground was such as 10
render the construction OF thoroughly tight and
stable basin somewhat difficult, but owing to the
small space available at the Washington yard. It
was necessary locate II fits present site. The
bottom Of the basin proper is made up Of a layer
Of broken stone which is a thin layer OF con-
crete then a half-inch Of Neuchate asphalt. then
about inches OF concrete in 16-foot lengths, the
bo.ur no lengths henR filed with
permudez asphalt and the whole inside surface
covered with the asphalt. The heavy side walls
are s feet thick at the Bottom, feet deep and
about feet inches thick the top. not count
Ing the moulded stone coping. They are In 4ofoot
lengths with d square key between adjacent
lengths filled with Bermudez asphalt. The side
walls rest on a double Of piles, and in ad-
dltion there is sheet-pling completely around the
deep part Of the tank The shallow part OF the
tank at the southern extension b also carried on
pHing 1t actually overhangs TIE water
The law authorizing the construction of the model
basin also authorized experiments to be made for
private shipbuilders, provided they betrayed the
actual cost OF the same IL being understood, OF
course. that such experiments should not interfere
with naval work This being the case, 1t was
necessary 10 lay out the plant with view to the
rapid and economical turning of routine expert
ments and to this end the endeavor has been
throughout 10 machinery for many OF the
operations as possible. The foreign tanks invari-
and generally make them from ten 10 fourteen feet
long. The climate OF Washington Is so warm in the
summer that II was found impossible 10 obtain
paraffine which would retain its rigidity setisfac-
toriy. and moreover IT was the desire Of the Bu-
reau OF Construction and Repair 10 make the
models as large a possible. thus eliminating one
source OF inaccuracy in applying the model expert
ments TO ful-sized ships For these reasons wood
was adopted the material for the models, and
after some difficulty satisfactory varnish was
10 - ne oil
intents and purposes absolutely water tight The
standard length OF the model used is twenty feet.
A model twenty feet long may not seem much
larger than one twelve feet long. but when II is
menlbered that the dispacements OF these two are
respectively 5000 and 172S 1t will be seen that the
2O-foot model is nearly five times the size OF the II
foot model
METHOD OF BUILDING MODELS.
The method Of building the models is as follows
The Zines Of the ship invariably include a body
plan giving sections at moderately close intervals
From this body plan new sections are drawn TO the
proper size for a N-foot model. by Of the
telegraph large pantograph shown in Fig.
These sections OF paper then trans
ferred 10 wooden boards. which are sawed TO shape
These boards then erected in their proper rela
tive position the erecting table each board sec
ton being clamped In a vertical plane They are
then covered with battens about one-half inch
thick and tapering from amdships toward the end
making q former model. the surface OF which Is
planed smooth. In cutting out the sections allow
ance made for the thickness of the battens which
have 10 be nailed them. Meanwhile a rough
block Of shapes and dimensions 10 enable the fn-
ished model TO be cut from 1t has been prepared
and glued together under pressure in large hy-
draulc press. This block is placed the upper
table OF the model cutting machine. the former
model being placed on the lower table. The model
cutting machine works upon the principle OF the
blanchard lathe a roller traversing the surface OF
the former model and saws or cutters working
upon the surface of the model proper The bulk OF
the material is removed from the block by means
Of the saws which shifted along short dis
lance at a time. Rotary cutters then applied.
which finish the surface of the model very close TO
the desired shape. The model is then removed from
the cutting machine and finished by hand, small
amount OF hand work. however, being found neces
sary. It is then ready for vanishing and the at
tachment OF any appendages such as bilge keels.
struts. etc. 1t is finally taken 10 the measuring
machine and careful measurements made OF It's
exact form and shape which not only enable the
staff to determine whether the model represents the
lines desired but gives exact record Of the actual
shape.
TOWING EXPERIMENTS.
The model is now ready for the towing expert
ments The carriage used in this work runs on
eight wheels and spans the full width Of the basin,
as shown The platform In the centre, carrying
the recording apparatus can be raised or lowered
at will Electricity is used 10 drive the carriage.
and IL may be mentioned incidentally that 1t is
used for all mechanical work in connection with
the model tank. The speed OF the carriage is
varied not only by making various combinations
OF the four motors-one 10 each pair OF driving
yheels-but by controlling the output Of the gen
orator in the power station, which is perhaps one
hundred yards from the tank. This control Is on
the Ward-Leonard system. and is similar TO that
used TO control the motion OF heavy turrets on
board ship. BY Of a resistance box on 'he
he through the nelO-cOn
o. the generator IL increased or decreased at Will
The revolutions OF the generator being Kept con-
slant by a delicate governor the amount OF cur
rent generated varies with the amount OF current