, 1859-10-22


The correspondent, ''vespertilio," writes to
The Loo odon 7ines Us follows;
] believe it cannot be too absolutely stated
that balloons are, md must he, incapable OF be-
ing directed. They are, and must be entirely
ut The mercy Of The current Of air in which they
float. This is q necessary condition Of their
buoyoncy. All tile aualcgles By which inven-
tnrs have been encouraged ia the delusiye hope
Of being nble to guide balloons ure false anafo-
gies. Tise r1ldaer8 OF ships and the tails of
birds have been uisquoted sadly. Ships donot
iloct suspended in one element alone, rs bal
looms loa: in the air. On the other hand. birds
are not buoyant, nor do they guide themselves
By their taiis, 4 ship does not float in the water
but on it; mud another element, on which she
does not float, is that in which she mainly
rnores. A bird does cot feat at all, either in
Tie nir or On it, in the proper sense Of that
term, that is to say. is not lighter, balloon
is, titan the element in which 1t moves, but ial-
mcpsely heavier. The condition of fsh under
water is more nearly like the condition Of bal
loon in the air; but there also essential dill
tescnccs. We may depend upon it that if We
IL s:re s so is iacps and Close
imitation Of the means which hare been desi2n-
I'd BIZ the Creator for eflecting the same pur-
pose in flying animals.
The problem Of :rrial navigation will nerer be
solved until the principles Of fight are clearly
understood, nor until we recognize precisely
what are the obstacles which prevent as from
acting upon them by artificial means. 1t is, Of
course, possible that these obstacles may prove
to be insuperable. / entertain u different in
preston but, ut MI crcnts. they cannot be
overcome until they are exactly known. I be-
licye them 10 be ali summed up in Que great de-
tict Of our present mechanical knowtedge-a
light motive power. l have yery little hope
tGat, until lighter motive power than steam is
discovered, nrial navigation will be accomplish
cd. but even with steam some experiments
might be tried which would test the principles
If flight, and at least lead the way in right d.
reetion for The p5ogrcs,s. Gi + discover; s.na
steam engine the perpendicular action Of d
birds wing. In truth the direct action Of 4
ristou would give this movement. ! rather
think this is the simple principle CT Nusmyths
| steam hammer. Would there be any difficulty
in making such piston work pair Of wings.
constructed on some such model as tue wings
| Of bat: What is the maximum velocity with
which such piston could he made to work q
! .iren area Of wing, or conversely, what Is the
maximum area Of wing which such m engine
could he made to work ut given velocity?
When these questions hare been answered BY
calculation OF experiment, the next step would
be to ascertain the lifting power Of such action
have no hope that any steam engine can be
1uade 50 light and 50 powerful as to work wing.
capable Of lifting its own weight In default o
any other means Of dealing with it, would sug
ccst that it be balanced By the lifting power 9
!. balloon. In this combination, be it observed
the whole machine would not he buoYant
Even this modified use Of a balloon is open II
Ireat objections, because the power exercisct
over it BY the slightest current air would b
very great aud the experiment could. only b
tried In Tranquil atmosphere; but, in detaul
Of any machine capable Of lifting the whole 6
its own weight, there seems to be no alternatis
Int to take of part Of the weight By balloon
My belief is, that such machine, when it aros
from the ground, would be found capable Of b.
inr directed, and TINT the direction of its figt
would be determined BY that in which its wing
| arcre ket