An essay on the first principles of natural philosophy. Wherein the use of natural means, or second causes, in the oeconomy of the material world, is demonstrated from reason, experiments of various kinds, and the testimony of antiquity : in four books illustrated with copper-plates / by the Reverend William Jones.

  • Jones, William, 1726-1800.
Date:
1762
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Licence: Public Domain Mark

Credit: An essay on the first principles of natural philosophy. Wherein the use of natural means, or second causes, in the oeconomy of the material world, is demonstrated from reason, experiments of various kinds, and the testimony of antiquity : in four books illustrated with copper-plates / by the Reverend William Jones. Source: Wellcome Collection.

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    ^-54 POST S -C R I p t; force, unlefs the body is examined independent of all active forces; which, I think, is not the cafe; and the reader, if he pleafes; may conlider of it. • On Chapter V. Page 44. 1. 21. Some other motions like to that of the two lamps may be contrived in a different manner. Fix a needle upon a pillar of glafs or fealing-wax four or five in¬ ches in length, and place a fmall wire upon it, pointed at each end, and bent into the fliape exprefled by Jig, 2. of plate-1, Let this little machine be fo placed, that you can eledlrify the brafs cap in its center by fparks from a wire hanging perpendicularly over it, but not touching it. If the inftrument is well made, and the fire ftrongly commu¬ nicated, the wire will turn upon its centre as fail as the fly¬ ers of a common jack: and if the room be darkened,, you will fee a ring of light formed by the electric asther as it ftreams from the points of the wire. This motion is fo far from being flopped or retarded by the refiflance of the circumambient medium, that there fcems to be no better method of accounting for it, than by deriving it immediately from fuch -a refiflance. The fire diverging from the points flrikes upon the adjacent air; while the air, readting againfl the flreams of fire, or rejifling them, gives a retrograde motion to the points of the wire; jufl as a chair, if placed upon caflers, will run backwards, when the perfon fitting in it puflies againfl the wall with a flick. If the wall were out of his reach, his flretching out the flick would make no imprelfion upon the chair: and the flreams of fire . . will