An introduction to the mathematical theory of attraction ...

PREFACE.
THE Theory of Attraction owes its origin to Newton. At
first its chief value lay in its connexion with Physical
Astronomy. The problems of the Figure of the Earth and
Precession gave rise to the splendid analysis of Laplace.
Towards the close of the last century the science of
Electricity began to be developed, and imparted a new and
a wider interest to the Theory of Attraction. Fresh problems
were offered for solution, and new modes of treatment were
devised by Physicists, among whom Gauss, Green, and
Thomson have been pre-eminent. The rapid progress of the
sciences of Electricity and Magnetism has been continually
increasing the direct value of the Theory of Attraction, but
its indirect value has become perhaps still greater.
For some time past Physical speculation has seemed to
point to the Theory of Fluid Motion as the root science of
nature. In recent times the investigations of Stokes, Thomson, and Helmholtz have shown that the leading problems
in the Theory of Fluid Motion are mathematically the same
as problems in the Theory of Attraction. This mathematical
similarity is to be found also, to a considerable extent, in the
Theory of Stress and Strain in Elastic Solids. The Theory
of Attraction is thus the portal to most of the higher departments of Mathematical Physics, and this is so even if it
should be shown that direct action at a distance does not exist
in nature.