Michael van Langren

Michael van Langren was the youngest member of a family of Dutch cartographers. He was baptized on 27 April 1598 in Amsterdam. His grandfather, Jacob van Langren, was born in Gelderland but moved to the Southern Netherlands and later to Amsterdam, where his sons Arnold and Hendrik were born. Unusually, each member of the family retained variations of Jacob's patronym Floresz rather than separate patronyms of their own. Jacob and his sons produced globes from 1580, both terrestrial and celestial. A 1586 pair survives, the celestial globe based on astronomical data provided by Rudolf Snellius father of Willebrord Snellius, while Petrus Plancius collaborated on the 1589 edition. In 1592, the States General granted the Van Langren family a monopoly in the production of globes, which led to quarrels with Jodocus Hondius. Arnold and Hendrik produced maps as well. Their world maps of the mid 1590s usually were drawn after maps by Plancius or Ortelius, but sometimes contained novelties based on recent discoveries such as depicting Nova Zembla as an island or Korea as a peninsula. Arnold moved with his family, which included his sons Jacob and Michael, from Amsterdam to Antwerp around the year 1609, during the truce between the Spanish crown and the States General. From the Spanish administration he got the title of and was awarded a grant of 300 livres towards the expense of his move. Michael van Langren did not receive a university education. He became a cartographer and engineer. He would serve as the Royal Cosmographer and Mathematician to King Philip IV of Spain, and was helped in his work by the patronage of Isabella Clara Eugenia. He died in May 1675 in Brussels. == Contributions ==

Among his contributions were attempts to determine longitude. Determining longitude at sea was one of the major scientific problems of the seventeenth century, and Van Langren devoted much of his work to finding a practical solution. As early as 1621 he proposed that longitude could be calculated by observing the Moon, particularly by tracking how the illumination of lunar mountains and craters changed during the lunar cycle. of statistical data, showing the wide range of estimates of the distance in longitude between Toledo and Rome.|left To show the magnitude of the problem, he created the first (known) graph of statistical data, showing the wide range of estimates of the distance in longitude between Toledo and Rome. He believed he could improve the accuracy of longitude determination, particularly at sea, by observing peaks and craters of the Moon as they appear and disappear, not only during eclipses of the Moon but also in the course of the entire lunation. His proposed method required accurate observations and detailed mapping of the lunar surface, which led him to undertake systematic studies of the Moon. He named crater Langrenus on the Moon after himself, and the name has been preserved to this day. ==External links==