Ever since the period when Newton established the great law of gravity, philosophers have occasionally speculated on the existence of some more comprehensive law, of which gravity itself is the consequence. Although some have considered it vain to search for a more general law, the great philosopher himself left encouragement to future inquirers; and the time, perhaps, has even now arrived, when such a discovery may be near its maturity. It would occupy too much space to introduce many illustrations of this opinion; there is, however, one which deserves attention, because it is not merely a happy conjecture, but the hypothesis on which it rests has been carried by its author, through the aid of profound mathematical reasoning, to many of its remote consequences.

M. Mosotti has shown, that by supposing matter to consist of two sorts of particles, each of which repels similar particles, directly as the mass, and inversely as the squares, of their distances; whilst each attracts those of the other kind, also according to the same law,—then the resulting attractions explain all the phenomena of electricity, and there remains a residual force, acting at all sensible distances, according to the law of gravity.

Many of the discoveries of the present day point towards a more general law; and many of the philosophers of the present time anticipate its near approach.