Omaha daily bee., 1916-05-10
The Force ~
that Keeps G
Zeppelin Up
by GARRETT =. SERVES,

Please explain whether the lifting ca
pacity OF Zeppelin type airship de-
creases as 4 ascends from me EARN =. ,,t u
OF the DIR or to the decreased pull OF tne
force OF gravitation2 When we say that
/ 4 Zeppelin can carry or lift thirty tons,
does that mean that the Weight OF ne
airshlp II thirty tons lighter than the
volume OF afr that It displaees2 Q. r.
Yes, the lifting capacity is measured
I by the difference between the weight OF
The balloon and the weight Of volume
Of air equal to the volume OF the balloon.
The air presses upward upon al bodies
Immersed in f. even when they are heav-
Ter than the air.
In the latter case they do not rise,
/ like a balloon, but they lose a certain
proportion of their weight II the at
mosphere we're suddenly removed every
/ thing on the earth would weigh more
than It did before. The force Of gravity
would be unchanged, but the buoyant
action Of the air would be gone.
This ia easily proved by experiment.
Take two bodies Of unequal density. like
wood and iron, and place them In the
opposite scales Of balance. In order
| that the beam may rest horizontal 1t is
necessary that the volume or size Of
the body having tho lesser density shall
be proportonately larger. Now. remove
them together with tho balance, into
vacuum, and tho beam will incline down
ward on the side Of The larger body be-
cause the air, which has been removed,
pressed upward more on that body than
on the smaller ONE.
A sla
her With gas heavier than sir the in
ellnsti6n OF tho beam would he reversed.
because the relative upward pressure on
the larger bo6y would Then be greater
than on the smaller ono, and 10 make
them balance az they did in air you
would have to decrease the. size IT the
larger body.
" TIE slr were ~ equal don Ivy from
bottom o top. balloon would mes er atop
until II got 10 the surface Of the atno
aphere. but-fhe density Of the mir de
crsa - rapidly with increase Of height
20 tbtt as he Balloon rises the difflrenca
between Us We ght ard that n an ea al
volume Of ar continually decreases un
NJ NJ 3 certain hight. which can DO
calculated by the formul9e employed ~
hypsone ry there win he no difference, i
and thtn TIE ball 1on can riSe no higher
The decrease of The force Of gravity A.
ouch beiehis ~ can be- attained by bal
loo = s relatively flight, ard hss no not
able effect on their buoSancyt Al 0
ight Of forr u lies a balloon would lose
only one .6o0th Of its weight
cubic foot ~ air at the eaTths sur.
face v e ehts about an ounce and n quar-
ter. although the weight Yafi with tn
temperature and the humidity cubic
ftot Of hydrogen in the same clrcum.
stances weighs about nine one hun
dredths ~ an ounce The differe1 nee, ll6
on lce, Ia the measure Of the buoyancy,
or II nR power, Of cubic foot Of hydro
gen immersed n air. and confined 70 that
hydrogen should be able 10 lift li6
o EEL 100 cube 10 I. tls ounce. an
90 cubic feet Ito ounces, or seventy
two and one-half pounds
But allowance must he made for tle
weight n the balloon. the ropes. the cage
. N everything that n carries n theEa
together amounted 10 seventy-two and
one hall pounds then the buoyancy Of
The l.tt0 ffft Of hydrogen would only SUI
lice to coun erhalance their weight with
,ut llftifg item from the ground.
Hut ~ me king The capacity Of the ga
bag 1900 (ub'c feet the Increase in weight
would he in onsiderable in comparison
With the Increase Of huoyancy which
would now amount to rs pounds But 10
get tho actual liftirg power consider
,hle margin must always be allowed for
'hange ~ temperature, humidity. etc. az
rell az for impurity Of the hydrogen Any
mixture 81 othrr Tas with It dimmiahea
ts buoyancy. The above estimates are
jrcb hly twI 2 TOO great
Space must be left IN the gas hag foi
he expansion Of the hydrogen as other.
Wise 4 would burst the bag as It ascende6
apidly. or else he forced out at the
'ottom. and thus a portion would be lost
The increase In the volume of the bal.
oon through the expansion Of the hydro.
ZEN. tends, up to a certain point n
the loss Of btsoyancy
through the decrease Of density In thu
surrounding air. But an elevation IA al.
rays reached where the huoyant force
eases 10 carry the balloon higher he
ause the volume Of air displaced exactly
qnals In weight the total weight or the
alloon with It's appurtenances
The same principle of huoyauey applies
! the case Of the immersion Of a body
water, II the density or specific gray.
~. ~ the body Is greater than that ~
'ater. II will sink 10 the bottom. n n
less II viii rise to the surface. Rut
here Is great difference between air
nd water with regard 10 compensatory
ir near the earth's surface IA very much
enser than az a height n a mtle or two.
nd the decrease of density continue
tth increase nf height Hnt the density
water b very slightly increased with
Icfease ~ depth. Consequently heavy
siy will never sten sinking 1t oncs il
ses under. but wdl descend 10 tho hot,
~.
Feeble aFe slil aesing ~ many letters
'esittd show whether the Titanic and
'e hnsitaois may not. be suspended
itnsNh Rrt hstwven the surface and tbe
'iiem n The sea That u Impossible.
asy lis on lha sea bed