Wallis, Dr., account of the Royal Society by, 14. Wealth, ways to acquire, 100. Wheel of life, Clerk Maxwell's, 297. Wilson, Dr., account of Cavendish by, 132, 147. Y. =Young=, Thomas, Principal Forbes's opinion of, 194; birth and parentage, 194; early education, 195; becomes a London medical student, 199; paper on the power of adjustment of the eye, 199; elected F.R.S., 200; visit to Cornwall, 201; first visit to the Duke of Richmond, 201; enters the Medical School at Edinburgh, 202; declines secretaryship to the Duke of Richmond, 202; visits Gordon Castle, 204; visits Inverary Castle, 205; enters the University of Goettingen, 206; examination in medicine at Goettingen, 207; enters Emmanuel College, 207; discovers the principle of interference, 208; appointed Professor of Natural Philosophy at the Royal Institution, 174, 210; lectures at the Royal Institution, 212; theory of colour-vision, 214; his colour-top, 215; colour-diagram, 215; his Bakerian lectures, 218; explanation of the rectilinear propagation of light, 221; of Newton's rings, 222; eriometer, 223; explanation of coloured halos, 224; of the colours exhibited by mother-of-pearl, 224; interference spectra, 225; explanation of spheroidal waves in Iceland-spar, 226; of the colours of thin plates, 227; hypothesis of an electric ether, 227; investigations on surface-tension, 229; modulus of elasticity, 230; his marriage, 231; appointed physician in St. George's Hospital, 231; superintendent of the Nautical Almanack, 232; death, 233. PRINTED BY WILLIAM CLOWES AND SONS, LIMITED, LONDON AND BECCLES. End of Project Gutenberg's Heroes of Science: Physicists, by William Garnett