owers. Da Vinci gave a clear exposition of the theory of
forces applied obliquely on a lever, discovered the laws of friction
subsequently demonstrated by Amontons, and understood the principle of
virtual velocities. He treated of the conditions of descent of bodies
along inclined planes and circular arcs, invented the camera-obscura,
discussed correctly several physiological problems, and foreshadowed
some of the great conclusions of modern geology, such as the nature
of fossil remains, and the elevation of continents. He explained the
earth-light reflected by the moon. With surprising versatility of genius
he excelled as a sculptor, architect, engineer; was thoroughly versed in
the astronomy, anatomy, and chemistry of his times. In painting, he
was the rival of Michel Angelo; in a competition between them, he was
considered to have established his superiority. His "Last Supper," on
the wall of the refectory of the Dominican convent of Sta. Maria delle
Grazie, is well known, from the numerous engravings and copies that have
been made of it.

ITALIAN SCIENTIFIC SOCIETIES. Once firmly established in the north of
Italy, Science soon extended her sway over the entire peninsula. The
increasing number of her devotees is indicated by the rise and rapid
multiplication of learned societies. These were reproductions of the
Moorish ones that had formerly existed in Granada and Cordova. As if
to mark by a monument the track through which civilizing influences had
come, the Academy of Toulouse, founded in 1345, has survived to our
own times. It represented, however, the gay literature of the south of
France, and was known under the fanciful title of "the Academy of Floral
Games." The first society for the promotion of physical science, the
Academia Secretorum Naturae, was founded at Naples, by Baptista
Porta. It was, as Tiraboschi relates, dissolved by the ecclesiastical
authorities. The Lyncean was founded by Prince Frederic Cesi at Rome;
its device plainly indicated its intention: a lynx, with its eyes turned
upward toward heaven, tearing a triple-headed Cerberus with its claws.
The Accademia del Cimento, established at Florence, 1657, held its
meetings in the ducal palace. It lasted ten years, and was then
suppressed at the instance of the papal government; as an equivalent,
the brother of the grand-duke was made a cardinal. It numbered many
great men, such as Torricelli and Castelli, among its members. The
condition of admissio