IX.—SIR WILLIAM THOMSON was born in Belfast in June 1824. His father, Dr. James Thomson, was a very remarkable man. The family of Thomsons had for several generations occupied a farm near Ballynahinch, in County Down, Ireland; but James Thomson, when quite a boy, endeavouring all alone to understand the principles of dialling, was led into the study of mathematics, for which it soon appeared that he possessed an extraordinary capacity. His father then permitted him to go to a small classical and mathematical school at his native place, and there he was soon promoted to be an assistant teacher. Without ceasing to labour as a teacher for his own support, he became a student in the University of Glasgow, attending there during the winter months, and teaching at Ballynahinch during the summer.