an exaggeration, it is certain that he possessed the rare power of being able to direct his attention to a very wide range of studies, though natural philosophy was certainly his special attraction. Whilst still presiding over his school, Gerbert produced several treatises on astronomy, mathematics, and geometry; on the formation of the astrolabe, the quadrant, and the sphere, as well as on rhetoric and logic. The monk Ditmar tells us that when at Magdeburg with his old pupil, Otho III., he made a clock, regulating it according to the movement of the polar star, which he observed through a kind of tube. Another writer speaks of certain hydraulic organs which he constructed, in which the wind and necessary movements were introduced by means of boiling water: and these obscure notices seem to indicate that wheeled clocks, the telescope, and the power of steam, were known by Gerbert fully three centuries before what has been considered their earliest discovery by our own Roger Bacon. Gerbert did not teach at Rheims alone. Crossing the Alps, he passed through most of the towns of Northern Italy, then subject to his great patron, Otho I. In 970 he also visited Rome in company with the bishop Adalberon, and at Pavia met the emperor, together with the celebrated Saxon, Otheric, whom we have seen filling the office of scholasticus in the episcopal school of Magdeburg. Otheric had up to that time enjoyed the reputation of being the greatest scholar of his age, and perhaps regarded himself somewhat in the light of a literary dictator. In the course of the previous year he had felt no little uneasiness at the daily increasing renown of the French professor, and had despatched one of his own Saxon pupils to Rheims to bring him an exact account of Gerbert’s method of dividing the sciences. The Saxon made an unsatisfactory report. It was Gerbert’s custom to represent physics and mathematics as equal and independent sciences. But Otheric’s disciple, whose head was none of the clearest, made him teach that physics were subordinate to mathematics, as the species to the genus. On this, Otheric decided that he knew nothing of philosophy, and proceeding to the court of the emperor, Otho I., he spoke to that effect before an assembly of learned men. Otho, who was himself passionately fond of these studies, was not satisfied, and resolved to sift the matter to the bottom. He therefore seized the occasion of Gerbert’s presence at Pavia to inaugurate a grand scientific tournament, and invited all the _savants_ of his empire to witness the dispute between the first scholar of France and the first scholar of Germany. He himself presided at the conference, and opened it with a brief allocution of his own, in which he very clearly explained the question in dispute. Then Otheric began his attack, first in words, and then in writing. The conference lasted the whole day, and Gerbert, who cited the authorities of Plato, Porphyry, and Boëthius,