GAUSS, KARL FRIEDRICH, an eminent German mathematician, was born of humble parents at Brunswick, April 23, 1777. He distinguished himself greatly while a student, and in his twenty-fifth year made his name widely known by his Disquisitiones Mathematicæ, a work full of the most subtle mathematical speculation applied to the higher branches of arithmetical science. In 1809 he published at Hamburg his Theoria Motus Corporum Cælestium, which gave a powerful impulse to the true methods of astronomical observation, towards which much care was at this period directed. Two years before this time he had been chosen director of the Göttingen Observatory, an office which he retained till his death, despite the many tempting offers he received of more honourable and lucrative positions elsewhere. So attached was he to his university, and so closely bent on his studies, that he never but on one occasion slept away from under the roof of his own observatory. In that solitary instance he had accepted an urgent invitation from Humboldt to attend a meeting of natural philosophers at Berlin. His only other acknowledged work, Theoria Combinationis Observationum Minime Erroribus Obnoxiae, appeared at Göttingen in 1823, and conferred a lasting boon on the cause of science; and many of his papers read before the society of Göttingen are hardly less valuable. Gauss was well versed in general literature and the chief languages of modern Europe, and was a member of nearly all the leading scientific societies of Europe. It is related that Laplace, when asked who was the greatest mathematician of Germany, replied, "Pfaff" (the teacher of Gauss). His questioner said he had thought Gauss even more profound. "Ah," said Laplace, "I esteem Pfaff the greatest mathematician in Germany; but Gauss the greatest mathematician in Europe." Gauss died at Göttingen early in the spring of 1855.