*THE POPULAR SCIENCE MONTHLY*

him a Gauss archive, in which the manuscripts of Gauss and other interesting material have been deposited. In the town of GĂ¶ttingen there is a statue of Gauss and his friend Weber, the physicist whom we have mentioned earlier. Gauss, in a sitting posture, and Weber, standing, appear engaged in a lively scientific discussion. Besides the telegraph, Gauss and Weber designed instruments which were used in the early determination of the magnetic elements of the earth's magnetism. Through Gauss's initiative there was established the German Magnetic

Union, with the object of securing systematic and continuous observations. Important as were Gauss's achievements in geodesy and the earth's magnetism, his chief scientific researches were in mathematics and astronomy. During his labors at GĂ¶ttingen, extending over nearly half a century, he made profound researches in the theory of numbers, which is one of the most subtle branches of mathematics. He greatly enriched by his investigations the theory of imaginary numbers, the