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Laws.
of Natural Philopoſophy.
19
Axioms or Laws of
Motion.
Law I.
Every body perſeveres in its ſtate of reſt, or of uniform motion in a right line, unleſs it is compelled to change that ſtate by forces impreſſ'd thereon.
PRojectiles perſevere in their motions, ſo far as they are not retarded by the reſiſtance of the air, or impelled downwards by the force of gravity. A top, whoſe parts by their coheſion are perpetually drawn aſide from rectilinear motions, does not ceaſe its rotation, otherwiſe than as it is retarded by the air. The greater bodies of the planets and comets, meeting with leſs reſiſtance in more free ſpaces, preſerve the motions both progreſſive and circular for a much longer time.
Law II.
The alteration of motion is ever proportional to the motive force impreſſ'd; and is made in the direction of the right line in which that force is impreſs'd.
If any force generates a motion, a double force will generate double the motion, a triple force triple the motion, whether that force be impreſſ'd altogether and
at
