ATTRACTION

(I.at. ad, to, and traho, /draw.) Used in physics to denote the tendency which we ol certain bodies to approach one another, and to re ration. The meaning of this term has been greatly obscured by metaphysical disputations, When a body A, is connected with another body 11, by a rod, or chain, or in general hy the intervention of any mechanical means, we see, or fancy we see, the reason why 1J attracts A, or A is compelled lo follow the motions of B. But when two distinct bodies not connectud by any vi Ible bond of union are observed to approach one another, tin phenomenon seems to a ume a greater degree of mystery, from our being no longer able to perceiy which ihe one body ii the other. On reflecting, however, on the constitution of material substanr. erinfl that they i dfatincl particles, which I reasons for bele ich other, we may soon satisfy ourselves that there much difficulty in conceiving how the different p a body cohere, or act on each other by lm| reiving how one body can be the cause of motion in another It is wrii remarked by Maupertuis, that the manner hi which the different properties reside inasubjecl Is always inconceivable to us. The vulgar are not astonished when they see a body in motion communicate its mi Don bocUM; we are accustomed to the phenomenon, which prevents our perceiving in it any thing marvellous. Hut philosophers will not readily believe that an Impul is more conceivable than an attractive one. what, in (act. is this impulsive force 7 How does it reside is Who could have predicted its existence before seeing the bodies impinge on each other? 'I' of other properties in bodies is not more clear. In what way does Impenetrability and the other come joined to extension? In these things there will always he mysteries Before the time of Sir Isaac Newton, the term attraction to denote a species of quality inherent in certain bodies; at the present time, however, philosophers use the won) not to expre any particular mode or species of action, or any physical cause of such action, hut simply the fact, that the different parts of matter tend to approach each other, without any reference to whether the power which produces that tendency is jnh< the lioilies, or consists in the expulsion of an external agent. They regard it as one of the ultimate phenomena to which the analysis of matter leads. Newton himself particularly cautions his readers against supposing that Ihere is really an attractive force residing in Ilie ci wards which bodies tend, the centres being only mathematical points. He takes care to mention that lie uses the term to denote a fact, and not a cause; that lie used il only for the purpose of avoiding systems and explli that this tendency might be caused hy some subtle matte] sionproceeding; but whatever from' bodies,its cause and be might the effect be, it of was a realclearlyimpul,s primary fact from which we might set out in explaining other facts depending on it. At present, objections of the sort which Newton here attempts tp avoid, cany little weight with them, but in the time of Newton they were ed of the greatest importance. Leibnitz called attraction an occult quality, a term then held in horror; and the fact is certain, that liie physical or metaphysical difficulties of explaining the nature of attraction contributed not a little to retard, on the Continent, the adoption of the Newton i an theory of the universe. Attraction, with reference to tho laws which it observes, maybe divided into two kinds; one, taking place among [s. 119]