Sir William Thomson, the greatest physicist of the age, and the highest authority on electrical science, theoretical and applied, was born at Belfast on June 25, 1824. His father, Dr. James Thomson, the son of a Scots-Irish farmer, showed a bent for scholarship when a boy, and became a pupil teacher in a small school near Ballynahinch, in County Down. With his summer earnings he educated himself at Glasgow University during winter. Appointed head master of a school in connection with the Royal Academical Institute, he subsequently obtained the professorship of mathematics in that academy. In 1832 he was called to the chair of mathematics in the University of Glasgow, where he achieved a reputation by his text-books on arithmetic and mathematics. William began his course at the same college in his eleventh year, and was petted by the older students for his extraordinary quickness in solving the problems of his father's class. It was quite plain that his genius lay in the direction of mathematics; and on finishing at Glasgow he was sent to the higher mathematical school of St. Peter's College, Cambridge. In 1845 he graduated as second wrangler, but won the Smith prize. This 'consolation stakes' is regarded as a better test of originality than the tripos. The first, or senior, wrangler probably beat him by a facility in applying well-known rules, and a readiness in writing. One of the examiners is said to have declared that he was unworthy to cut Thomson's pencils. It is certain that while the victor has been forgotten, the vanquished has created a world-wide renown.