Spiral with intersecting radii, 1687.
© Science Museum / Science & Society Picture Library
Proposition 15, Theorem 12, concerning the revolving motion of bodies in resisting mediums from Newton's 'Principia Mathematica' (1687): 'If the density of a medium in every place is inversely as the distance of places from a motionles centre and if the centripetal force is in the squared ratio of the density, I say that a body can revolve in a spiral that intersects in a given angle all the radii drawn from that centre.' The discoveries of English physicist and mathematician Isaac Newton (1642-1727) were prolific and hugely influential on science and thought. His work included the three laws of motion, the theory of gravitation, the law of cooling, the binomial theorem and the calculus.