474 Artificial Flight . [July, 
Mr, Wenham, in his Paper read at the first meeting of 
the Aeronautical Society, says — “ Having remarked how 
thin a stratum of air is displaced beneath the wings of a 
bird in rapid flight, it follows that, in order to obtain the 
necessary length of plane for supporting heavy weights, the 
surfaces may be superposed, or placed in parallel rows, with 
an interval between them. A dozen pelicans may fly one 
above the other without material impediment, as if framed 
together ; and it is thus shown how two hundredweight may 
be supported in a transverse distance of only io feet.” But 
I think that the difficulty of actuating the wings of these 
twelve mechanically imitated pelicans would present as great 
a difficulty as the vibration and construction of wings of the 
dimension of “ 60 feet from end to end, and 4 feet across at 
the widest part,” which in the same Paper Mr. Wenham 
estimates as necessary to support the weight of a man. If 
to this we add the weight of motive power — for it is evident 
that man does not possess the necessary power — we might, 
but for other encouraging reasons, give up the hope of his 
ever being able to navigate the air, because its possibility, in 
the way that a bird flies, is held to rest either upon the 
necessary surface extended laterally or else superposed, and 
in either case — were the difficulty overcome — there would 
remain the important question of balance, which in the bird is 
maintained, I believe, similarly to that unconscious muscular 
action in the sole of the foot and leg, when a man stands in 
an upright position. Under such a surface, therefore, there 
would be, I maintain, no safety. 
I grant that a light and very powerful motor would favour- 
ably alter some of these conditions, because the rapid 
vibration of a much smaller surface would effeCt the same 
result, but increase of strength of structure would be 
necessary. 
I had hoped that some rotatory action, which would have 
presented to the air in rapid succession all the equivalents 
of flight by wing-surface, would have solved the difficulty ; 
but the only attempt hitherto made in that direction has 
been effected by Mr. Moy, at a cost of several hundred 
pounds. The velocity which was requisite in its preliminary 
run was fatal to the attempt, because it could not be attained 
even if the machine had been effective on leaving the ground. 
Then what has man to propose to evade these difficulties, 
which appear insuperable ? Need I mention that he resorts 
to balloon propulsion in one of the various forms which 
are always recurring to minds who take freshly to the sub- 
ject, and which are always supposed to be new, 
