Physicist and mathematician. Born in Dalkeith. He was educated at Dalkeith Grammar School and then Edinburgh Academy with James Clerk Maxwell (1831-79), who became a life-long friend. Noted for his remarkable intelligence, his education continued at the University of Edinburgh and Peterhouse College, Cambridge. Tait was appointed as Professor of Mathematics at Queen's College, Belfast, in 1854. Although most of his work was theoretical he undertook experiments on electrical discharge through gases while there. He next gained the Chair of Natural Philosophy at Edinburgh (1860), a position for which Maxwell had been a candidate. Tait's other interests included magnetism, quaternions, knot theory, graph theory and thermodynamics. With William Thomson, Lord Kelvin, (1824 - 1907), Tait wrote the important Treatise on Natural Philosophy, published in 1867. Jointly with Balfour Stewart, he wrote The Unseen Universe (1867) which was in such demand that they followed it with a sequel Paradoxical Philosophy (1878). Tait also wrote a classic paper on the trajectory of golf balls, his son Freddie Tait (1870 - 1900) having been a champion golfer.
He died in Edinburgh and lies buried in the churchyard of St. John's Episcopal Church on Princes Street. The Tait Professorship of Mathematical Physics remains an established Chair within the University of Edinburgh.