"Newton's system was for a long time considered as final and the task... seemed simply to be an expansion.... From the theory of the motion of mass points one could go over to the mechanics of solid bodies, to rotatory motions, and one could treat the continuous motion of fluid or the vibrating motion of an elastic body. All these... were gradually developed... with the evolution of mathematics, especially of the differential calculus... checked by experiments. and hydrodynamics became a part of mechanics. Another science... was astronomy. Improvements... led to... more accurate determinations of the motions of the planets... When the phenomena of electricity and magnetism were discovered, the... forces were compared to the gravitational forces... Finally, in the nineteenth century, even the theory of heat could be reduced..."