1879J 
477 
Artificial Flight . 
forward without much affedling the stability of the machine. 
His descent under the parachute adtion can thus be gradu- 
ated at will. This can also be effected by a cord attached to 
the tail, which by that means can be elevated or depressed 
at pleasure. Placed upon wheels it has, of course, yet to 
be ascertained what distance of preliminary run would be 
required, assisted by the adfion of the fabric, before it would 
rise from the ground. 
In Mr. Linfield’s construction I see the framework 
required. The alteration would be flexible arms, and I think 
a looser arrangement of the cloth. The treadle action might 
or might not be able to vibrate the wing-arms. These flexible 
arms I construct of a bundle of canes, about 12 or 14 feet 
long, bound tightly together with whipcord throughout their 
whole length, and cutting off a cane every 2 feet or so in 
order to taper them. The wing-arm then affords lightness 
combined with strength, for it is almost impossible to fraCture 
it. In this case we should be spared the weight of the screw, 
which is something considerable. 
It has to be determined by experiment what velocity and 
what arc of vibration is best suited to the weight to be sus- 
tained. There will be also some relation between the arc of 
vibration of the wing-arm and the amount of surface in 
undulation. 
In the model which I have made there exists a strong 
illustration of the assertion that any device made in minia- 
ture which will fly, can, when constructed upon a scale of 
utility, perform not only all, but much more than all, the 
promises extracted from it in the model form. In the first 
place, the experimenter is greatly in want of some motive 
power which will last sufficiently long to allow of close ob- 
servation. Now in the recoil of the india-rubber which I have 
employed to produce the revolution of the crank which 
vibrates the arms, there exists only power sufficient to give 
a dozen strokes or so. And were I to increase the throw of 
the crank so as to increase the arc of vibration at the end of 
the wing, I should require so much greater power that either 
I could not with my own exertions wind it up, or else the 
parts would fail to bear the strain. For want of that con- 
tinuous power I cannot say what amount of weight the 
model which I have made will carry, but I know this to a 
certainty, viz., that the weight to be carried depends upon 
the power and the strength of material for a given surface 
kept in a state of vibration. The weight of the larger model 
is 3 lbs. ij ounces, of which 7 ounces is added weight, which 
it easily carries. The dimensions are 6 feet wide by 10 feet 
