1800. ] 
the wings, making complete revolutions 
xound the fhip, and proceeding with great 
Velocity either with or againft the, wind.’ 
I have feen them as near as ten or twelve 
feet, and have watched them with the ut- 
moft attention, without perceiving the 
{mallet motion in ‘the wings’or tail. It 
has been faid, that this motion, which is 
called foaring, is produced by a perpetual 
{mall vibratory motion of the wings; but 
this appears to me to be without any 
foundation; the form of the wings in the 
bird of which Lam writing is by no means 
adapted to fuch a quick motion, nor is it 
conceivable, that in wings fo long as are 
thofe of this bird in queftion, a motion of 
this kind fhould not become perceptible at 
the [mall diftances at which I have feen it 
pafs. 
Now, although the conformation of the 
animal is fo ingenioufly adapted to mecha- 
nic flight, yet fomething more feems to be 
neceflary. A progreflive motion of the 
whole body, with a velocity of fifteen or 
twenty or probably more miles ip an 
hour, is produced, and that either with or 
againtt the wind, or in adead calm. How 
is this motion caufed? By what power is 
the body impelled with fo confiderable a 
velocity? There is no perceptible motion 
of the wings, no mechanical principle to 
which we can have recourfe; and I can 
only account for it, by fuppofing it to be 
the immediate effect of a mental energy, 
a volition, the mind acting upon matter. 
Something analogous to this we find in our 
mufcular motion, when from a ftate of 
reft a limb is put into action; but that 
which in this cafe extends only toa limb, 
extends in the bird to the whole body; as 
we feel a confcioufnefs that cur muticles 
will move in obedience to our volitions, fo 
the bird muft feel a confcicufnefs of a 
power of wafting himfelf through the air 
in all directions. Of the mode of action 
of the mind upon body we know but little ; 
we mark the effect, and there our knowledge 
ceafes. - 
On communicating this idea to a friend, 
whofe fupericr endowments I have ever 
bowed to with deference; he objected, 
«< That to account for the flight of a bird, 
hy faying it was the effe&t of a volition, did 
not feem to him to excite any new;ideain his 
mind,or to advance his knowledge; tor who 
ever doubted, that the flight of birds was 
as much conreéted with volition as the 
walking of a man, the galloping of a horfe, 
the {kipping of a monkey, or the {wimming 
of a fifh: that although we may not be 
able to difcern the mechanical part of the 
flight, it is too much to infer that it does 
On the Flight of Birds. 
127 
not exift; that to. account for two things 
fo much alike as the flight of one {pecies 
of birds and that of another, or perhaps of 
two fets of motion in the fame bird, by 
principles fo different, was contrary to all 
analogy ; and that all birds which foar have 
remarkable long wings, which feems to 
have regard to mechanifm.”’ 
He further alleged, ‘* That a perfon on 
feeing, for the firft time, an expert fkaiter, 
might with equal feeming reafon fuppofe 
that motion to be the immediate effect of a 
volition, as the motion generated feems fo 
difproportionate to the original impetus ; 
and if this motion, in which the body meets 
with the refiftance of one medium more than 
the bird, may be caufed by fuch a trifling 
original impulfe, may-not the bird, sliding 
through a free medium, be fuppofed to be 
eafilywafted through a much greater {pacey 
by a {mall occafional impulle from the mo- 
tions of the wings and the tail?” All this, 
I readily allow, is ingenious and forcible, 
and [ doubt not will to many appear per- 
fecily fatisfactory, without having recourfe 
to any principle befides the one ulually ad- 
mitted. But I muft fay, that my mind is 
not fatished with this reafoning.—i do not 
contend for any diftinétion in the. nature 
of the volitions of the birds and other ani- 
mals, but for the degree of their influence 
on matter ; when a man walks, avhorfe 
gallops, or a monkey jumps, the original 
motion in the mufcles of the limbs, trom 
a previous ftate of reft, is doubtlefs pro- 
duced by the action of mind upon body $ 
but the progreflive motion of the whole 
body is cauled mechanically, and may be 
explained by the principle of the action and 
reaction of matter Upon matter; and coulda 
machine be contrived fimilar in form to either ’ 
of theabove mentioned animals,and a filer 
motion or conatus to motion be impreffed 
upon the limbs, the progreflive motion 
of the whole body would be produced as in 
the Jive animal; there is a feries of mo- 
tions in the parts from which relults the 
progreffive motion of the whole ina ftraight 
line. But in the flight of the bird of which 
Tam writing, every thing is different, the 
parts are ali relatively at reft, while the 
whole proceeds forward with the very con- 
fiderable degree of velocity abcve-men- 
troned. In one cafe there is a feries of 
motions interpofed between the original 
volition, and the ultimate effect on the 
whole body ; in the other there is no fuch 
interpofition, and the whole boey is ap»pa- 
rently wafted through the air, in direct obe~ 
dience to the will, The length and the 
fize of the wings affift in fupporting the 
bird in the air, by acting as a parachute ; 
R 2 but 
