Balfour Stewart

Balfour Stewart (1 November 1828 – 19 December 1887) was a Scottish physicist and meteorologist.

His studies in the field of radiant heat led to him receiving the Rumford Medal of the Royal Society in 1868. In 1859 he was appointed director of Kew Observatory. He was elected professor of physics at Owens College, Manchester, and was the first holder of the prestigious Langworthy chair that he retained until his death on 19 December 1887. He was the author of several successful science textbooks, and also of the article on "Terrestrial Magnetism" in the ninth edition of the Encyclopædia Britannica.

Career

Stewart was born on 1 November 1828 at 1 London Row in Leith (north of Edinburgh), the son of William Stewart a tea merchant, and his wife, Jane Clouston. His father was involved in business in Great Britain and Australia.

He was educated at Dundee. He then studied physics at the University of St Andrews, and the University of Edinburgh. Following his studies of physics at Edinburgh, he became assistant to James David Forbes in 1856. Forbes was especially interested in questions of heat, meteorology, and terrestrial magnetism, and it was to these that Stewart also mainly devoted himself.

Radiant heat first claimed his attention, and by 1858 he had completed his first investigations into the subject. These yielded a remarkable extension of Pierre Prévost's "Law of Exchanges," and enabled him to establish the fact that radiation is not a surface phenomenon, but takes place throughout the interior of the radiating body, and that the radiative and absorptive powers of a substance must be equal, not only for the radiation as a whole, but also for every constituent of it.