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.

Francesco Lana, son of a noble family, was born in 1631; in 1647
he was received as a novice into the Society of Jesus at Rome,
and remained a pious member of the Jesuit society until the end
of his life. He was greatly handicapped in his scientific
investigations by the vows of poverty which the rules of the
Order imposed on him. He was more scientist than priest all his
life; for two years he held the post of Professor of Mathematics
at Ferrara, and up to the time of his death, in 1687, he spent
by far the greater part of his time in scientific research, He
had the dubious advantage of living in an age when one man could