Can't let the day fade without the mention of Vincenzo Viviani born on this date in 1622.
Bill Ashworth in the Linda Hall Library Newsletter wrote...
When just a lad of 16, Viviani so impressed the Duke of Florence with his mathematical talent that he was assigned as secretary to the aging and blind Galileo. Viviani moved into Galileo's villa at Arcetri and lived there for the last three years of Galileo's life. After Gaileo's death in 1642, Viviani published several important mathematical works of his own, but he gave high priority to his role as conservator of Galileo's memory and work. In 1654, he wrote a biography of his hero; it was intended for inclusion in the 1656 edition of Galileo's Opere, but it was not published there, instead appearing only in 1717. Nevertheless, Viviani’s Life of Galileo was the principal source for information on Galileo until the 20th century. And in it are two famous stories: one says that Galileo discovered the law of pendulums by observing the swinging chandeliers in the Pisa Cathedral; the other states that Galileo demonstrated the fallacy of Aristotle’s laws of falling bodies by dropping weights from the top of the Tower of Pisa. Both stories became part of Galileo lore and are still often retold. Neither story, alas, appear to be true. We have a pretty little 1826 edition of Viviani’s Vita di Galileo in the History of Science Collection, as well as the monumental Opere di Galileo, published in 20 volumes between 1890-1909, and made possible by Viviani’s diligent collecting of Galileo’s manuscripts and correspondence.
Vincenzo Viviani [Wikipedia]
h=l + m + nVincenzo Viviani is also the formulator of a geometry theorem named after him...the Viviani theorem where "...the sum of the distances from a point to the sides of an equilateral triangle equals the length of the triangle's altitude."
Viviani's theorem [Wikipedia]