Book reviews: The wonderful geometry of dynamics

S. Chandrasekhar, Newton's Principia for the Common Reader : Oxford University Press, 1995. ISBN 0-19-851744-0 Copies of Cajori’s translation of Newton’s Principia and of Whiston’s Sir Isaac Newtons Mathematick Philosophy More Easily Demonstrated (Senex & Taylor, 1716) have rested on my shelves for some years. Nevertheless, I had only dipped into them to compare Mach’s criticisms with Newton’s discussions of the fundamentals, and to read his proofs of some of the crucial theorems, such as: ‘there is no gravitational field anywhere inside a gravitating shell of uniform matter bounded by two similar concentric ellipsoids’. Reading Chandrasekhar’s book has introduced me to much more of Newton’s masterpiece. Chandrasekhar’s novel approach to understanding Principia is to set himself to prove the major propositions by modem methods, and then to follow Newton’s proofs. He succeeds in putting Newton’s propositions into a far more readable form, and in comparing the relative dullness of the more modem, manipulative methods with the greater insight generated by geometry. Some years ago, after much debate, geometry as known to Euclid was dropped from the British school curriculum.