cter. He informs the correspondent through whom Cosmo's offer
was conveyed, that his salary of 520 florins at Padua would be increased
to as many crowns at his re-election, and that he could enlarge his
income to any extent he pleased, by giving private lectures and
receiving pupils. His public duties, he stated, occupied him only sixty
half-hours in the year; but his studies suffered such interruptions from
his domestic pupils and private lectures, that his most ardent wish was
to be relieved from them, in order that he might have sufficient rest
and leisure, before the close of his life, to finish and publish those
great works which he had projected. In the event, therefore, of his
returning to Pisa, he hoped that it would be the first object of his
serene highness to give him leisure to complete his works without the
drudgery of lecturing. He expresses his anxiety to gain his bread by his
writings, and he promises to dedicate them to his serene master. He
enumerates, among these books, two on the system of the universe, three
on local motion, three books of mechanics, two on the demonstration of
principles, and one of problems; besides treatises on sound and speech,
on light and colours, on the tides, on the composition of continuous
quantity, on the motions of animals, and on the military art. On the
subject of his salary, he makes the following curious observations:--

"I say nothing," says he, "on the amount of my salary; being convinced
that, as I am to live upon it, the graciousness of his highness would
not deprive me of any of those comforts, of which, however, I feel the
want of less than many others; and, therefore, I say nothing more on the
subject. Finally, on the title and profession of my service, I should
wish that, to the title of mathematician, his highness would add that of
philosopher, as I profess to have studied a greater number of years in
philosophy, than months in pure mathematics; and how I have profited by
it, and if I can or ought to deserve this title, I may let their
highnesses see, as often as it shall please them to give me an
opportunity of discussing such subjects in their presence with those who
are most esteemed in this knowledge."

During the progress of this negotiation, Galileo went to Venice, on a
visit to a friend, in the month of April or May 1609. Here he learned,
from common rumour, that a Dutchman had presented to prince Maurice of
Nassau an optical instrument, which possess