Adrien left for Paris during the 1640s, where he developed an interest in astronomy and became well known in academic circles.
[1] In 1664–1665 he made observations of comets, and argued in favor of their following elliptical or parabolic orbits (in this he was opposed by his rival Johannes Hevelius).
[3] He then left for Italy and spent the next 20 years in that country, finally dying in Rome in 1691.
In 1647 he performed an experiment that demonstrated the role of air pressure in function of the mercury barometer.
In 1667–68, Auzout and Jean Picard attached a telescopic sight to a 38-inch quadrant, and used it to accurately determine positions on the Earth.