Mathematicians Helping Sailors 1564 (Portugal) 1 Bound volume, manuscript on parchment, 29 folios; 31,5 × 21,5 × 1,5 cm Torre do Tombo National Archives of Portugal PT/TT/MSLIV/0869 Many scientific and technical developments made during the 16th century, in response to the new needs of oceanic navigation, were adaptations of previously existing procedures. Both nautical instruments and nautical techniques were frequently adapted from instruments and methods that astronomers and astrologers had used for many centuries. Astronomical techniques were also adapted to solve navigation issues, such as calculating the current latitude, a crucial operation for any venture on the high seas. This process of progressive adaptation was complex and required the joint collaboration of sailors and scholars such as mathematicians, professional groups that had very little in common up to that time. The manuscript presented here records astronomical data necessary for the determination of latitude. M...