BOSCOVICH'S THEORY theory of natural philosophy which claims Boscovich for its author, has attracted, in no small degree, the attention of the learned : And although we are by no means disposed to imagine, that much, j progress is likely to be made in physical science by the original excogitation, or by the general applica tion of theories of any kind, and are rather inclined to fall in with the opinion of the celebrated Bacon, that mankind are much more liable to be seduced into the winding mazes of error and fancy, than di rected in the more difficult path of truth and know ledge, by that fondness for systems, and those habits of generalization, to which they are so much addict ed ; yet this theory has appeared so specious, so general in its application, and so well adapted to the explanation of most of the difficulties that occur is physical science, that we have thought it would be proper to if our readers such an account of it, at least, as, i not sufficient to render them masters of the ingenious conceptions of its author, may per haps induce them to search for farther information, in the works of the illustrious Ragusan.
This theory is alleged, by Boscovich, to hold the Y mean between those of Leibnitz and of Newton ; since it admits, with the former, that the elementary par ticles of matter are simple and unextended ' • and with t the latter, that they act on each other by. mutual Z forces, which are variable at different distances.
We may add too, that, with Leibnitz and his fol lowers, Boscovich argues strenuously for the exist ence of the general law of continuity.. While, with the followers of Newton, he admits, in general, the actio e distanti ; and also agrees with them in their ideas respecting light, gravity, the pressure of fluids, &c.
But from the Leibnitzian this theory differs wide ly, in• not admitting that continued extension can arise from contiguous and inextended atoms ; a dif ficulty long ago urged against the system of Zeno : and also, in alleging, that the ultimate particles of matter are homogeneous, in opposition to the princi ples of indiscernibles, and the sufikient reason urged against that doctrine by the disciples of Leibnitz.
From Newton also he conceives himself to differ, in explaining by one law of forces, not only all those phenomena (and many more) for which the former author, in his last optical query, seems to think three principles were requisite, viz. gravitation, cohesion,
and fermentation ; but also in alleging, that, at the least distances, the mutual forces are not attractive, - 3 but repulsive ; and that this repulsive force, with the diminution of distance, increases in infinitum. Of course, it necessarily follows, that cohesion does not arise from absolute contact of parts ; and that, in fact, absolute mathematical contact, as it is called, cannot possibly exist.
Let us now proceed to unfold the theory. The first elements of matter, according to Boscovich, are, points altogether inextended and indivisible, dissemi nated in an immense vacuum, and placed at certain distances asunder. These distances may be increased or diminished, but cannot altogether vanish, without an absolute compenetration of particles ; for their pos sible he altogether denies. These par ticles he conceives endued with inertia • persever ing, if single, in their state of rest, or uniform'recti lineal motion.
He conceives two of these points of matter to have a determination, at some distances, to approach each other ; at others, to recede : and this he calls, the force attractive or repulsive, the magnitude of which changes with the distances, according to some law which may be expressed by an algebraical formula, or, as is common in mechanics, by a curve line. This law of the forces is such, that, in the smallest distances, it is repulsive, increasing indefinitely as the distance is diminished ; and is therefore equal to the extinction of any force of approach, however great. At a dis tance somewhat greater, this force diminishes, so that a very little way off, it vanishes entirely : be yond that, the force becomes attractive, which, as we continue to pass outward, arrives at its maximum, then diminishes and vanishes • after that, a repulsive force takes place again, which, in its turn, increases to a maximum, then diminishes and vanishes ; and thus,' passing through several alternations until we arrive, at length, at 'a force constantly attractive, but diminishing inversely as the square of the dis-. tance, which continues at least as far as the limits of our planetary system, and is no other than the ge neral law of Newtonian gravity.