(1821-1895) English mathematician who developed matrix algebra, used by Werner Heisenberg in his elucidation of quantum mechanics. He also developed the study of n-dimensional geometry, introducing the concept of the “absolute”, and formulated the theory of algebraic invariants.
Cayley was born in Richmond, Surrey, and studied mathematics at Cambridge before becoming a barrister. In 1863 he became professor of pure mathematics at Cambridge.
Cayley published about 900 mathematical notes and papers on nearly every pure mathematical subject, as well as on theoretical dynamics and astronomy. Some 300 of these papers were published during his 14 years at the Bar, and for part of that time he worked in collaboration with James Joseph Sylvester, another lawyer. Together they founded the algebraic theory of invariants 1843. Cayley clarified many of the theorems of algebraic geometry that had previously been only hinted at, and he was one of the first to realize how many different areas of mathematics were drawn together by the theory of groups.

(1886-1950) Australian ornithological artist who specialized in Australian birds. His best-selling book What Bird is That? first appeared in 1931 and gives color illustrations and descriptions of all Australian birds.

(1773-1857) English aviation pioneer, inventor of the first piloted glider 1853, and the caterpillar tractor.
Cayley was born in Brompton, Yorkshire. In later life he helped to found London's Regent Street Polytechnic.
Cayley spent much of his life experimenting with kites and gliders, but also worked on other aspects of flight, including helicopters, streamlining, parachutes, and the idea of biplanes and triplanes. The 1853 glider was a triplane, in which his reluctant coach driver traveled 275 m/900 ft across a small valley—the first recorded flight by a person in an aircraft. Although delighted with the result, Cayley realized that control of flight could not be achieved until a lightweight engine was developed to give the thrust and lift required.