Chap. 5. PHILOSOPHY. 251

been fhewn, that the fun attracts the primary planets, andtheir refpedive fecondary, when at the fame diftance, foas to communicate to both the fame degree of velocity;and therefore the force, wherewith the fun ads on the fe-condary planet, bears the fame proportion to the force,wherewith at the fame diftance it attracts the primary, asthe quantity of folid matter in the fecondary planet bears tothe quantity of matter in the primary.

?. This property therefore is proved of both kinds ofplanets, in refped of the fun. Therefore the fun poflefles thequality found in the earth, of ading on bodies with a de-gree of force proportional to the quantity of matter in thebody, which receives the influence.

6 . That the power of attradion, with which the otherplanets are endued, fhould differ from that of the earth, canhardly be fuppofed, if we conflder the ffmilitude betweenthofe bodies; and that it does not in this refped, is fartherproved from the fatellites of Saturn and Jupiter, which are at-\traded by their refpedive primary according to the fame law,that is, in the fame proportion to their diftances, as the prima-ry are attraded by the fun: fo that what has been concludedof the fun in relation to the primary planets, may be juftlyconcluded of thefe primary in refped of their fecondary, andin confequence of that, in regard likewife to all other bodies,viz. that they will attrad every body in proportion to thequantity of folid matter it contains.

Hence

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