A system of mechanics, being the substance of lectures upon that branch of natural philosophy / By T. Parkinson.

  • Parkinson, Thomas, 1745-1830.
Date:
1785
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Licence: Public Domain Mark

Credit: A system of mechanics, being the substance of lectures upon that branch of natural philosophy / By T. Parkinson. Source: Wellcome Collection.

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    Thus the attraftion of gravity is difcovered, by experiments and aftronomical obfervations, to pervade all matter with which wc are acquainted : all bodies near the earth’s furface, and the rnoon, gravitate towards the earth 3 the waters of the fea gravitate towards tne moon 3 the fun, planets, and comets, gravitate to- # wards each other mutually3 and of this principle no bodies ac- ceftible to experiments can be diverted, and therefore, from this rule, it is inferred to be an univerfal attribute of matter. 9- As much falfe philofophy hath been difleminated by fanciful hypothefes and mere metaphytical confiderations, unfupported by the reality of facts, the only fources of natural fcience, the utility of the following rule is apparent. RULE IV. In experimental philofophy, proportions cdiecled from phenomena by induBion are to be deemed, notwithji ending contrary h:pot he fey either accurately true or very nearly fo 3 until other phenomena occur by which they may be rendered either more accurate, or liable to exception. 10. The exirtence, quantity at a given diftance, and law of va- riation at different diftances, of any natural power being demon- ffrated by the analytic method of reafoning, the only way by which they can be known 5 they are affumed as eftablifhed gene- ral principles, and their adequacy to the produdtion of other phenomena, fimilar to thofe ufed in the analyfis, is proved fyn- thetically. Examples illuftrating the fynthetic method of reafoning. Examp. I. The influence of the attraction of gravity, its quantity and law of variation, being afeertained analytically, it is affumed as an eftablifhed general principle, and demonftrated geo- metrically to be an adequate caufe of the motions of pendulums, projeftiles, preceflion of the equinoxes, irregularities of the moon’s motion, riling and ebbing of the fea, and innumerable other phe- nomena. Examp.