PART I: THE EVOLUTION OF THE AEROPLANE

II. EARLY EXPERIMENTS ( Page 8 )   <<Previous   Next >>

Continued from page 7......
But they are far below such excess, for the aforesaid pectoral muscles do not equal a hundredth part of the entire weight of a man. Wherefore either the strength of the muscles ought to be increased or the weight of the human body must be decreased, so that the same proportion obtains in it as exists in birds. Hence it is deducted that the Icarian invention is entirely mythical because impossible, for it is not possible either to increase a man's pectoral muscles or to diminish the weight of the human body; and whatever apparatus is used, although it is possible to increase the momentum, the velocity or the power employed can never equal the resistance; and therefore wing flapping by the contraction of muscles cannot give out enough power to carry up the heavy body of a man.'

It may be said that practically all the conclusions which Borelli reached in his study were negative. Although contemporary with Lana, he perceived the one factor which rendered Lana's project for flight by means of vacuum globes an impossibility--he saw that no globe could be constructed sufficiently light for flight, and at the same time sufficiently strong to withstand the pressure of the outside atmosphere.

He does not appear to have made any experiments in flying on his own account, having, as he asserts most definitely, no faith in any invention designed to lift man from the surface of the earth. But his work, from which only the foregoing short quotations can be given, is, nevertheless, of indisputable value, for he settled the mechanics of bird flight, and paved the way for those later investigators who had, first, the steam engine, and later the internal combustion engine--two factors in mechanical flight which would have seemed as impossible to Borelli as would wireless telegraphy to a student of Napoleonic times. On such foundations as his age afforded Borelli built solidly and well, so that he ranks as one of the greatest--if not actually the greatest--of the investigators into this subject before the age of steam.

The conclusion, that 'the motive force in birds' wings is apparently ten thousand times greater than the resistance of their weight,' is erroneous, of course, but study of the translation from which the foregoing excerpt is taken will show that the error detracts very little from the value of the work itself. Borelli sets out very definitely the mechanism of flight, in such fashion that he who runs may read. His reference to 'the use of a large vessel,' etc., concerns the suggestion made by Francesco Lana, who antedated Borelli's publication of De Motu Animalium by some ten years with his suggestion for an 'aerial ship,' as he called it. Lana's mind shows, as regards flight, a more imaginative twist; Borelli dived down into first causes, and reached mathematical conclusions; Lana conceived a theory and upheld it-- theoretically, since the manner of his life precluded experiment.

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