New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1911-05-28
International Hotel

culties experience in the early Inhexible
experiments. This he did by reducing the
size of the tanks and placing the motion
OF the contained water under proper con-
troll
Perhaps it WIFI be as we'll just here to
quote from Herr Frahm's paper: This
result has been obtained by the most care
full application Of the laws of resonance.
Under the effects of resonance
bodies that can oscillate about a condition
Of equilibrium are made 10 swing severely
under comparatively small impulses az soon
as the period of oscillation Of the impulse
is synchronous with the individual periods
of the respective bodies. a ship constitutes
a body OF this kind, she will osclllate
under the impulse Of the waves AS Is well
known, a ship will roll almost exactly in
the periods of her individual oscillations.
Large heeling ampltudes can he
produced on a ship only il she is struck
by series Of comparatively regular
waves, and struck In the measure OF her
individual number Of oscillations Under
such circumstances the influence Of res
onance will he promptly felt. and there
will be an increase OF the angle of heeling
tudes observed in practical seafaring are
due merely 10 the influence OF resonance
between wave and vessel on this fact the
present device has been based. II utizes
secondary and artificial resonance in
order to annihlate the influence of the
primary resonance between waves and
ship. This secondary resonance is intro
duced ny means OF U-shaped tank, To-
Gated athwartship and extending from side
TO side i'm which water column can os-
cillate with the same number Of swings a
minute that are peculiar 10 the shin her
self The ship will heel only as far
a. the water. under the action Of secondary
resonance, rises or falls in the vertical
tanks TO such an extent that the heeling
moment impaired 10 the ship by the
waves Is balanced by the opposite turning
moment. produced by the oscillations OF the
water. The increment OF heelng from i'm
pulse 10 impulse, In free ship cannot take
place now. and the rolling motions will be
limited 10 such as will he sufficient TO pro-
duce the necessary oscillations Of the tank
water"
In the earlier tanks a free wave rolled
from side to side i'm an open chamber.
is inclosed In a carefully dimensioned
chamber, where it performs uniform move
ments. which can he controlled by blocking
the connections. The tank consists Of two
capacious chambers. one on each side of
tho ship. connected at the bottom by a
shallow passage for the transference of the
water. Curved diaphragms leading from
this passage into the side chambers act as
ba ria n vol 1a o,j
passage connecting the upper parts of the
vertical tanks is provided with a throttling
air valve, by which the passage of the air
IL is forced from side to side of the shin
by the rising and falling of the water can
he INSTRUCTED with view 10 adjusting the
oscillations OF the tank water TO the con-
dtiOn Of the sea. Also by closing the
valve the movement of the water may he
blocked.
The first experiments were made on the
passenger steamers Ypiranga and Corco-
vado These vessels are Az feet long and
have loaded displacement of 14iCL tons.
The tanks are placed above the waterline.
there being one forward and one aft Of the
amidship deckhouse The total quantity of
water in each tank il % tons In rough
weather during voyages from Germany To
Argentina or Mexico 1t was found that the
rough weather heeling angles OF IL degrees
To either side were reduced when the roll
ing tanks were i'm action TO only degrees
TO 2is degrees on another occasion When
the tanks were out OF action the shin WAS
rolling Is degrees on each side OF the verti-
cal; but when the tanks were liberated the
rolling reduced to from 3 to degrees
When the tanks are In full actor they
exert turning movement of a79O-foot tons.
Scientific American