Ostilio Ricci, a professor at the Drawing Academy in Florence and a personal friend of Vincenzo Galilei's (c.1520-1591), helped Galileo in his study of Euclid (4th century B.C.) and Archimedes (287-212 B.C.), thus contributing to his decision to abandon the study of medicine for that of mathematics. Ricci had been a pupil of Niccolò Tartaglia (1499-1557), an acclaimed mathematician from Brescia, and he had developed a strong interest in military architecture and applied mathematics. An interest he did not fail to communicate to Galileo, who taught these subjects in turn, as testified by his Breve instruzione all' architettura militare [Brief Introduction to Military Architecture] and Trattato di fortificazione [A Treatise on Fortification], something like handouts which he used in teaching the many private students he had in Padua.