A SYSTEM OF MECHANICAL PHILOSOPHY. BY JOHN ROBISON, LL. D. LATE PROFESSOR OF NATURAL PHILOSOPHY IN THE WITH NOTES, By DAVID BREWSTER, LL. D. FELLOW OF THE ROYAL SOCIETY OF LONDON, AND SECRETARY TO THE ELECTRICITY. We cannot but be somewhat surprised that, among the many attempts which have been made by the philosophers of Britain to explain the wonderful phenomena which are classed under the name of Electricity, no author of eminence, besides the Honourable Mr. Cavendish and Lord Mahon, have availed themselves of their susceptibility of mathematical discussion; and our wonder is the greater, because it was by a mathematical view of the subject, in the phenomena of attraction and repulsion, that the celebrated philosopher Franklin was led to the only knowledge of electricity that deserves the name of science; for we had scarcely any leading facts, by which we could class the phenomena, till he published his theory of positive and negative, or plus and minus, electricity. This is founded entirely on the phenomena of attraction and repulsion. These furnish us with all the indications of the presence of the mighty agent, and the marks of its kind, and the measures of its force. Mechanical force accompanies every other appearance; and this accompaniment is regulated in a determinate manner. Many of the effects of electricity are strictly mechanical, |