Of a Vacuum in the Heavens, and between the Parts of Bodies: with an Experimental CHAP. I. Some positive Proofs, that a Medium, dif ferent from the Rays of Light, is present in the Heavens; with an Answer to a common Objection from some Experiments with the Barometer.. CHAP. II. Some positive Proofs, that a Medium, en- dued with very great Force, is present between the Interstices of grosser Bodies, and in other Spaces CHAP. III. Of the Physical Cause of Cohesion.... CHAP. IV. An Experiment to confirm and illustrate what has been advanced in the foregoing Chapter: with some Observations on Heat and Cold...... CHAP. V. Of the Physical Cause of Repulsion; par- CHAP. I. Some General Observations on the Learning CHAP. II. Teftimonies from the principal Authors of Profane Antiquity among the Greeks..... CHAP. III, Some Observations on the Remains of CHAP. IV. Some Extracts from two Authors among the Latins, Pliny and Seneca; with some Reflections CHAP. V. The Sentiments of the most eminent of the Modern Writers subjoined to those of the Ancients..328 AN ESSAY, &c. BOOK I. On the Mechanism of Nature; or the Use of natural means in the producing of physical effects. CHAP. I. The Introduction. Some occasional reflections on the prejudices of Philosophers. Apology for the Author, with an account of his design. Two different systems of Philosophy briefly explained. GOD OD having created the world for the benefit of all mankind, every man has a natural liberty of inquiring into the structure of it, and examining the various motions that appear in it, with their several depend VOL. VIII. B dependences, circumstances, and causes: a study highly commendable, if confidered only as an inexhauftible fund of innocent amusement, but worthy of a better name, when applied to its proper use: for if it be not our own fault, we may, out of the good things that are seen, know him that is; and, by considering the works, be led to acknowlege the power, goodness, and unspeakable wisdom of the workmaster. In this inquiry, though a man may reap many advantages by seeing with the eyes of others, who could see farther than himself, and is greatly to be blamed if he does not make use of the opportunity; there is certainly no law that obliges him to keep his eyes fhut, where his own safety and satisfaction require him to open them. The constitution of the world, together with the powers, causes, or principles upon which the operations of nature depend, being matters of fact, and not points of speculation, it is evidence alone that can lead us to any rational determination. My design at present, therefore, is to collect as much of this evidence as the case can reasonably be thought to require, and lay it before the public, without any regard to to the systematical reasonings, or reputed authority, of this or that philosopher in particular. In the prosecution of this design, I shall endeavour to express my mind with freedom and impartiality, as a man ought in conscience to do, who has no private ends to serve, and does not desire that the value of what he has written fhould be determined by the favour of his friends, but rather that his enemies, if he has any, would rigorously compare it with their own observation and experience. If we are not free from those vulgar prejudices-that it is a great misfortune to be. singular-that the multitude (who have been always changing) must necessarily be in the right-and that the last writer, who has obtained a name in any subject, is to be followed implicitly in every thing he has propounded; we fhall be afraid to inquire, and to endeavour to advance the progress of true and useful knowlege, as we all profess to do, and all ought to do; but shall rather fall upon the fruitless labour of accommodating every new discovery to the principles we have already received, looking at the same time. with a suspicious eye on every writer, who, with regard to any particular article, would |