ted in drawing round him the scientific genius of
the age. He was a member of the celebrated Lyncaean Society, founded by
Prince Frederigo Cesi; and though he is not known as the author of any
important discovery, yet he has earned, by his liberality to science, a
glorious name, which will be indissolubly united with the immortal
destiny of Galileo.

The subject of floating bridges having been discussed at one of the
scientific parties which had assembled at the house of Salviati, a
difference of opinion arose respecting the influence of the shape of
bodies on their disposition to float or to sink in a fluid. Contrary to
the general opinion, Galileo undertook to prove that it depended on
other causes; and he was thus led to compose his discourse on floating
bodies,[25] which was published in 1612, and dedicated to Cosmo de
Medici. This work contains many ingenious experiments, and much acute
reasoning in support of the true principles of hydrostatics; and it is
now chiefly remarkable as a specimen of the sagacity and intellectual
power of its author. Like all his other works, it encountered the most
violent opposition; and Galileo was more than once summoned into the
field to repel the aggressions of his ignorant and presumptuous
opponents. The first attack upon it was made by Ptolemy Nozzolini, in a
letter to Marzemedici, Archbishop of Florence;[26] and to this Galileo
replied in a letter addressed to his antagonist.[27] A more elaborate
examination of it was published by Lodovico delle Colombe, and another
by M. Vincenzo di Grazia. To these attacks, a minute and overwhelming
answer was printed in the name of Benedetti Castelli, the friend and
pupil of Galileo; but it was discovered, some years after Galileo's
death, that he was himself the author of this work.[28]

[25] Discorso intorno alle cose che stanno in su l'acqua, o che in
quella si muovono. Opere di Galileo, vol. ii. pp. 165-311.

[26] Opere di Galileo, vol. ii. pp. 355-367.

[27] Ibid. 367-390.

[28] These three treatises occupy the whole of the third volume of
the Opere di Galileo.

CHAPTER IV.

_Galileo treats his opponents with severity and sarcasm--He is
aided by the sceptics of the day--The Church party the most
powerful--Galileo commences the attack, and is answered by Caccini,
a Dominican--Galileo's Letter to the Grand Duchess of Tuscany, in
support of the motion of the Earth and the