1434 by Gavin Menzies Page B

We know from the Yuan Shi-lu, the official history of Yuan dynasty, that this astronomical data was included in the Shoushi calendar, and one can see a copy of the 1408calendar in the Pepys Museum in Cambridge, England. Two pages are shown on our 1434 website.
    When the Chinese visited Florence in 1434, Toscanelli was in his prime, thirty-seven years old. Since graduating from university twenty years earlier, he had worked with Brunelleschi, a mathematical genius, and other leading intellectuals of the day. In particular, Toscanelli and Brunelleschi had, for the previous thirteen years, been collaborating on the complex spherical trigonometry required to build Florence’s great dome over Santa Maria del Fiore. Toscanelli thus had ample opportunity to observe and accurately map the heavens in detail before the Chinese visit, but neither he nor any other of his circle did so. Toscanelli was a secretive bachelor who lived with his parents until they died, after which he lived with his brother’s family. Although he never cited a particular influence or source for the prodigious mathematical and astronomical skills he displayed after 1434, he did bequeath a considerable collection of books, research papers, astronomical instruments, and world maps to his monastery. All but one of these have disappeared. Aside from that one remaining record—a manuscript housed at the Biblioteca Nazionale Centrale in Florence—we are left primarily with admiring references to him in letters among his friends. But we do know a bit about his actions. Did he behave differently after 1434? If so, how?
    Jane Jervis, in “Toscanelli’s Cometary Observations: Some New Evidence” 8 examined Toscanelli’s surviving manuscript, a collection of folios. She compared the writing on the folios with that on the letters from Toscanelli to Columbus and Canon Martins and concluded that all but three of the folios were written by Toscanelli. Jervis then compared Toscanelli’s study of two comets—one in 1433, before the Chinese visit, and another in 1456, after the visit. Folios 246 and 248 describe the 1433 comet; folios 246, 252, and 257 describe the 1456 comet.
    The first comet pass was on Sunday, October 4, 1433, in the first hour of the night. Toscanelli’s observations consist of a freehand drawing. He did not align the comet’s positions with any stars or planets. No times are listed, nor are right ascensions or declinations of the stars or comets.
    This is in stark contrast with Toscanelli’s treatment, twenty-three years later, of the 1456 comet. Folios 246r and v, 252, and 257 contain a wealth of evidence. For the 1456 comet, he uses a Jacob’s staff to give the comet’s altitude (declination) and longitude (right ascension) to within ten minutes of arc. 9 Times are now given, as are the declination and right ascensions of the stars (Chinese methods). To achieve this radical improvement in technique, Toscanelli must have had a clock, an accurate measuring device, astronomical tables, and an instrument to show the position of the comet relative to stars and planets.
    If true, James Beck’s deduction that Alberti was assisted by Toscanelli in drawing the precise positions of stars, moon, and sun at noon on July 6, 1439 on the dome in the Sacristy of San Lorenzo similarly suggests a great leap in Toscanelli’s scientific capabilities. For many years prior to 1434, Toscanelli had the opportunity to use the dome of Santa Maria del Fiore for astronomical observations. Yet he never did.
    By 1475, Toscanelli had adopted a Chinese type of camera obscura, a slit of light and a bronzina (bronze casting), which he inserted in the lantern of the dome of the Florence cathedral. The pinhole camera has several advantages when measuring objects illuminated by the sun. The edges of the circle receive less exposure than the center. Since the focal length of an object’s edges is greater than that of its