Great physicist, born at Belfast; studied at St. Peter's College, Cambridge; was senior wrangler in 1845, and elected professor of Natural Philosophy in Glasgow in 1846; it is in the departments of heat and electricity he has accomplished his greatest achievements, and his best-known work is the invention of the siphon-recorder for the Atlantic cable, on the completion of which, in 1866, he was knighted, to be afterwards raised to the peerage in 1892; he has invented a number of ingenious and delicate scientific instruments, as well as written extensively on mathematical and physical subjects; b . 1824.