206 Natural and Artificial Flight. [Arril, 
a brief interval, the flame of the candle was persistently 
blown from right to left. I then waited until the flame of 
the candle assumed its normal perpendicular position, after 
which I caused the wing to make another and opposite 
sweep from left to right. The wing again rose kite fashion, 
and the flame was a second time affected, being blown in 
this case from left to right. I now caused the wing to 
vibrate steadily and rapidly above the candle, with this 
curious result, that the flame did not incline alternately 
from right to left and from left to right; on the contrary, 
it was blown steadily away from me, 7.e., in the direction of 
the tip of the wing, thus showing that the artificial currents 
produced met and neutralised each other always at mid 
stroke. I also found that under these circumstances the 
buoying power of the wing was remarkably increased.” 
‘“How the Wave Wing creates Currents, and rises upon them, and 
how the Air assists in elevating the Wing.—In order to ascertain 
in what way the air contributes to the elevation of the wing, 
I made a series of experiments with natural and artificial 
wings. On concluding these experiments, I felt convinced 
that when the wing descends it compresses and pushes 
before it, in a downward and forward direction, a column 
of air corresponding to its area. The air rushes in 
from all sides to replace the displaced air, and so produces a 
circle of motion. The wing rises upon the outside of the 
circle referred to, so that it is not difficult to comprehend 
how the air comes indirectly to assist in elevating the wing. 
The artificial currents produced by the wing during its 
descent may be readily seen by partially filling a chamber 
with steam, smoke, or some impalpable white powder, and 
causing the wing to descend in its midst.” 
“ The Artificial Wave Wing as a Propelley—The wave wing 
makes an admirable propeller if its tip be directed vertically 
downwards, and the wing be lashed from side to side by a 
sculling figure-of-8 motion, similar to that executed by the 
tail of the fish. Three wave wings may be made to act in 
concert and with a very good result; two of them being 
made to vibrate in a more or less horizontal direction with 
a view to elevating, the third being turned in a downward 
direGtion, and acting at right angles to the others for the 
purpose of propelling.” 
“4 New Form of Aérial Screw.—If two of the wave wings 
represented at Fig. 15 be placed end to end, and united to 
a vertical portion of tube to form a two-bladed screw, 
similar to that employed in navigation, a most powerful 
elastic aérial screw is at once produced, as seen at Fig. 16. 
