Part 32

Thomson's, Professor James, application of the principle of dissipation of energy to the freezing of water under pressure, 327.

Thomson's, Sir William, statement of the principle of dissipation of energy, 327; vortex theory of matter, 312; mirror galvanometer, 313; replenisher, 316.

Thunder-storms, Franklin's theory of, 81.

Torpedo, Cavendish's experiments on the, 140; Davy's experiments on the, 251.

Traction of carriages, Rumford's experiments on, 189.

Trial plate used by Cavendish, 139.

Tyres, relative advantages of broad and narrow, 189.

Undulatory theory founded by Hooke and Huyghens, 218.

Union of the American States, Franklin's plan for, 68.

University of Philadelphia, foundation of the, 64.

Vacuum, Boyle's argument on the cause of a, 23.

Velocity of electricity, 93; of light measured by Roemer, 2; of light deduced from electro-magnetic theory, 306.

Viscosity of gases explained by Maxwell, 299.

Voltaic pile constructed by Faraday, 241.

Vortex theory of matter, 312.

Voss machine, 316.

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.

=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.

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