TAIT, PETER GUTHRIE Scottish physicist, was born at Dalkeith on April 28, 1831. After attending the Academy at Edinburgh and spending a session at the University, he went up to Peterhouse, Cambridge. As a fellow and lecturer of his college he remained in Cambridge until 1854, and then left to take up the professorship of mathematics at Queen's col lege, Belfast. There he joined Thomas Andrews (a.v.) in re searches on the density of ozone and the action of the electric discharge on oxygen and other gases. From 186o to 1901 he was professor of natural philosophy at Edinburgh, where he died on July 4, 1901.
His earliest work dealt mainly with mathematical subjects, and especially with quaternions (q.v.), of which he may be re garded as the leading exponent after their originator, Hamilton. With the help of Hamilton and Philip Kelland (1808-1879), he wrote two text books, Elementary Treatise on Quaternions (1867), and Introduction to Quaternions (1873). He also pro duced original work in mathematical and experimental physics. In 1864 he published a short paper on thermodynamics, and from that time his contributions to that and kindred departments of science became frequent and important. He worked on thermo electricity and thermal conductivity, its variation with temperature and its relation to the electrical conductivity of the same ma terial. (See HEAT.) From 1879 to 1888 he was engaged on difficult experimental investigations, which began with an inquiry into the corrections required, owing to the great pressures to which the instruments had been subjected, in the readings of the thermometers em ployed by the "Challenger" expedition (q.v.) for observing deep sea temperatures, and which were extended to include the com pressibility of water, glass and mercury. Between 1886 and
1892 he published a series of papers on the foundations of the kinetic theory of gases; and about the same time he carried out investigations into impact and its duration.
A selection only from his papers, published by the Cambridge Uni versity Press, fills three large. volumes. With Lord Kelvin he collab orated in writing the well-known Treatise on Natural Philosophy. "Thomson and Tait," as it is familiarly called, but only the first part of it was ever completed.
Tait collaborated with Balfour Stewart in the Unseen Universe which was followed by Paradoxical Philosophy.
the chief city of the province of Shansi, China, first noticed about A.D. 450, but greatly developed after the ex pulsion of the Mongols by the building of a great wall in 1377. Its exposure to attack from Mongolia was the reason for this. It is situated on the Fen-ho river, in a well-peopled plain with many good villages, and is at an altitude of about 2,56oft. above sea-level. The valleys of the plain nearly all have coal mines, and coal is taken by cart to the capital, the population of which was estimated, early in the century, at a quarter of a million, but has been more recently calculated at about 8o,000. It formerly made weapons. It has a university and is the terminus of a railway line from the east, which branches from the Peking Hankow main line. Meteorological observations kept here show a rainfall of 11.6in. per annum, mainly from May to August, more than half the total falling in July, the month of highest average temperature (76.6°). The January average temperature is as low as 18.o°, and in most years a temperature as low as is the average minimum for that month.