Artificial Flight . 
473 
1879.] 
vapour that rises from the earth : — 1. The vapour of the 
soil is much warmer at night than the air, and would be 
condensed by it. 2. Vapour from the soil is soon diffused 
and equalised in the whole atmosphere, but in largest pro- 
portion when evaporation is taking place near the surface of 
the soil ; and, other things being equal, plants nearest the 
earth have the most dew. 3. Dew under haycocks, boards, 
and like objedts on the ground, could receive it from no 
other source . — Kansas City Review of Science and Industry, 
IV. ARTIFICIAL FLIGHT* 
By F. W. Brearey, 
Honorary Secretary to the Aeronautical Society. 
OTLN the Paper which I read before the Aeronautical Society 
at the General Meeting in 1878 1 stated that, with 
respedl to those of my models which are actuated by 
wing-movement, I had found a difficulty of sustaining the 
weight which appertains to the living example. But from ex- 
periments which I have lately made I find that the weight to 
be sustained depends upon power and strength of material 
employed, and also upon the right application of that power. 
For instance, in the wing-adlion of the bird, that portion of 
the pedloral muscle which depresses the wing is considerably 
more powerful than that which elevates it, because its func- 
tion is to sustain the whole weight of the bird by impadl upon 
the air. In my models I attain that adtion by affixing india- 
rubber cord, more or less in tension (according to the power 
used), underneath the wings, so that when the wings 
are elevated there shall be a strong downward impetus. 
There is, however, a disadvantage not shared by the bird, 
— the upward stroke in the model absorbs much power 
in working against the tension of the india-rubber under- 
neath. Given that power, and with material to endure the 
pressure considerable weight can no doubt be sustained, 
What immediately concerns us, however, is this : — Can the 
weight equal to that of a man and the additional power 
necessary to propel him be sustained by any material which 
man can construct; light enough and strong enough ? 
* A Paper read before the Aeronautical Society of Great Britain: 
VOL. IX. (N.S.) 2 I 
