It was a stormy night in February 15 of the year 1564 when I was born, in Pisa Italy. I was one of six children of Vincenzo Galilei. My full name is Galileo di Vincenzo Bonaiuti de' Galilei, At the age of 8, my family moved to Florence, but I was left with Jacopo Borghini for two years. I then was educated at Camaldolese Monasteryat Vallombros.
I had a medical degree at the University of Pisa at my father's urging but I did not complete this degree, but instead I studied mathematics. In 1589, I was appointed to the chair of mathematics in Pisa. In the year 1591 my father died. In 1592, I moved to the University of Padua, teaching geometry, mechanics, and astronomy until 1610. During this period I made significant discoveries in both pure fundamental science as well as practical applied science (for example, strength of materials and improvement of the telescope). My multiple interests included the astronomy. Based only on uncertain descriptions of the first practical telescope, invented by Hans Lippersheyin the Netherlands in 1608.in the following year, I made a telescope with about 3x magnification. I later made improved versions with up to about 30x magnification. With a my telescope the observer could see magnified, upright images on the earth, it was what is commonly known as spyglass. I could also use it to observe the sky for a time I was one of those who could construct telescopes good enough for that purpose. I made original contributions to the science of motion through an innovative combination of experiment and mathematics. More typical of science at the time were the qualitative studies of William Gilbert, on magnetism and electricity. My father, Vincenzo Galilei, a lutenist and music theorist had performed experiments establishing perhaps the oldest known non-linear relation in physics: for a stretched string, the pitch varies as the square root of the tension. These observations lay within the framework of the Pythagorean tradition of music, well-known to instrument makers, which included the fact that subdividing a string by a whole number produces a harmonious scale.
Although, a limited amount of mathematics had long related music and physical science, and when I was young could see my own father's observations expand on that tradition. I also discovered that all planets are round including earth and that earth wasn’t flat. My theoretical and experimental work on the motions of bodies, along with the largely independent work of Kepler and René Descartes, was a precursor of the classical mechanics developed by Sir Isaac Newton. My mathematical methods were the standard ones of the day. The analysis and proofs relied heavily on the Eudoxian theory of proportion, as set forth in the fifth book of Euclid's Elements .My early works describing scientific instruments include the 1586 tract entitled “The Little Balance “(La Billancetta) describing an accurate balance to weigh objects in air or water and the 1606 printed manual Le Operazioni del Compasso Geometrico et Militare on the operation of a geometrical and military compass. In the beginning of January 1642 I felt very ill and passing away at the age of 77 and I wished to be buried next to my fathers and other ancestors in Basilica of Santa Croce.