Page:Popular Science Monthly Volume 66.djvu/263

Rh wished his brilliant son to adopt the lucrative profession of medicine. Galileo's early inclinations seem to have been to become a painter. The boy was educated at the monastery of Vallombrosa, where he learned Latin, some Greek, a little logic. He was an excellent pupil, but as his eyes were affected his father removed him and, at the age of seventeen (1581), sent him to study medicine at Pisa. He was already a clever musician, witty, eloquent, with a strong talent for painting, and had laid the foundations of a literary style which Italians estimate highly. In his later years Galileo knew the poems of Ariosto by heart. His general health was not good, but he was amiable, gay, versatile, fond of society and also very fond of a country life and of his vineyards and groves. He was considerate and liberal to his family, devoted to his children. His friends loved him ardently, and his enemies were equally constant in their dislike. The characteristics of his maturer life were in evidence throughout his youth also. His powers of observation were extraordinarily quick. He was a philosopher, also, from the first, and very expert in all mechanical matters.

Before the high altar of the cathedral at Pisa hangs a lamp,—a masterpiece of Maestro Possenti. Watching its swingings to and fro one day Galileo, then a student, observed that although the amplitude of the swings diminished the time of oscillation remained the same (1583). From this chance observation resulted the law: The time of oscillation of a pendulum is independent of the amplitude of its swings. If this be true (and it is true when the amplitudes are small), the pendulum can be used to measure, with precision, intervals of time. A hundred of its swings will always require the same time whenever the arc of swinging is not large. The first application of this discovery was the invention of a pendulum suited to measure pulse-beats. Towards the end of his life Galileo endeavored to construct a pendulum clock. He was engaged in this research at the time of his death, aided by his son Vincenzio, who carried on the work. A short pendulum beats more quickly than a long one. The law of the relation of length to period was also discovered by Galileo. It is: The lengths of pendulums are proportional to the squares of the times of oscillation. A pendulum beating seconds is four times as long as one beating