<P> "I deduced that the forces which keep the planets in their orbs must be reciprocally as the squares of their distances from the centres about which they revolve, and thereby compared the force requisite to keep the moon in her orb with the force of gravity at the surface of the earth and found them to answer pretty nearly ." </P> <P> So Newton's original formula was: </P> <Dl> <Dd> F o r c e o f g r a v i t y ∝ m a s s o f o b j e c t 1 × m a s s o f o b j e c t 2 d i s t a n c e f r o m c e n t e r s 2 (\ displaystyle (\ rm (Force \, of \, gravity)) \ propto (\ frac (\ rm (mass \, of \, object \, 1 \, \ times \, mass \, of \, object \, 2)) (\ rm (distance \, from \, centers ^ (2))))) </Dd> </Dl> <Dd> F o r c e o f g r a v i t y ∝ m a s s o f o b j e c t 1 × m a s s o f o b j e c t 2 d i s t a n c e f r o m c e n t e r s 2 (\ displaystyle (\ rm (Force \, of \, gravity)) \ propto (\ frac (\ rm (mass \, of \, object \, 1 \, \ times \, mass \, of \, object \, 2)) (\ rm (distance \, from \, centers ^ (2))))) </Dd>

Who laid down the first accurate laws of motion for masses