During the years 1613 to 1621 Morin was employed by the Bishop of Boulogne. He was sent to Germany and Hungary. His main task seems to have been to visit mines and make studies of metals. His skill in astrology seems to have been his main use to the Bishop.
His next employer was the Duke of Luxembourg, for whom he worked until 1629. During this period Morin published a defence of Aristotle (1624) and he also worked on optics. However astrology remained his main interest although he worked with Gassendi on observational astronomy.
Morin was appointed professor of mathematics at the Collège Royal in 1630 and he was to hold this post until his death. From about the time of his appointment he attacked Galileo and his views. He was to continue his attacks against Galileo after the trial of 1633. Morin remained firmly convinced that the Earth was fixed in space.
Morin is best remembered for his attempts to solve the longitude problem. His solution, proposed in 1634, was based on measuring absolute time by the position of the Moon relative to the stars. He was certainly not the first to propose the method but he did add one important new piece of understanding, namely he took lunar parallax into account.
Since Morin put forward his method for a longitude prize, a committee was set up by Cardinal Richelieu to evaluate it. Étienne Pascal, Mydorge, Beaugrand, Hérigone, J C Boulenger and L de la Porte served on the committee and they were in dispute with Morin for the five years after he made his proposal.
Morin realised that instruments had to be improved, improved methods of solving spherical triangles had to be found and better lunar tables were needed. He made some advances in these areas but his method, although theoretically sound, could not achieve either the computational or observational accuracy to succeed. Morin refused to listen to objections to his proposal.
Even while the dispute was going on, in 1638, Morin attacked Descartes saying that he had realised as soon as they met how bad his philosophy was. These disputes alienated Morin from the scientific community. He was to spend the latter part of his life isolated from other scientists although Cardinal Richelieu's successor Cardinal Mazarin did award him a pension for his work on the longitude in 1645.
Article by: J J O'Connor and E F Robertson
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