His universal law of gravitation explained many things, including the action of tides & the motion of comets
In it Newton proposed universal gravitation and the inverse square 
law of... [DOC] [TLE] Universal Gravitation  The Physics Hypertextbook [PAR] It should be noted that Halley did not discover the comet that bears his name, ... 
chapters on mechanics in every subsequent physics textbook, including this one.