Astronomy improved: or, A new theory of the harmonious regularity observable in the mechanism or movements of the planetary system : In three lectures, read in the chapel of Yale-College, in New-Haven. Begun February 17, 1781. Exhibiting a new and accurate method, for investigating the velocities, distances and periods of the planets; founded on the nature of gravitation, and mathematical relations and dependencies between their distances, velocities and periods: as also for finding the quantities of matter in the primary planets; and the figure of the moon's orbit in open space. By Nehemiah Strong, M.A. Professor of mathematics and natural philosophy in that college. Published for the use, and at the desire of the students. [Four lines of Scripture texts].