GREENHILL, SIR ALFRED GEORGE English mathematician, born in London on Nov. 29, 1847, was educated at Christ's Hospital and St. John's college, Cambridge. He held the posts of fellow and lecturer in mathematics at Emmanuel college, Cambridge (1873-76), and professor of mathematics to the advanced class of artillery officers, Woolwich (1876-1906). He retired in 1906, and occupied himself with activities connected with the Royal Society and the London Mathematical Society. Greenhill was a member of many foreign learned societies; and received many academic honours, includ ing a knighthood in 1908. He died in London on Feb. 1o, 1927.
Greenhill's mathematical work consisted of original contribu tions to dynamics, hydrodynamics and elasticity. In these he made extensive use of elliptic functions and also applied the sigma-functions due to Weierstrass. The investigation of the problem of the steadiness of flight of a projectile due to rifling and the amount of rifling required for various types of projectile was very warmly received at Woolwich. He applied elliptic func tions to the investigation of special problems for the advisory committee on aeronautics and he issued two reports, the first on Stream Line Motion past a Plane Barrier (1910), and a sup plementary report dealing with curved boundaries in 1916. An other well known problem solved by Greenhill was that of the greatest height a vertical shaft can attain without bending under its own weight. He tested his solution by the measurement of the heights of trees. Greenhill wrote Hydrostatics (1894) , Dif ferential and Integral Calculus (1886), Applications of Elliptic Functions (1882), Notes on Dynamics (1908).
See obituary notice by Love in Journal of the Londcn Mathematical Society, vol. iii. (1928).