or admit that, in the Saturnian realms, there can be motion regulated by laws which we are unable to explain." Maxwell then showed that the rings, if either solid or liquid, would break into pieces, and concluded as follows: "The final result of the mechanical theory is, that, the only system of rings which can exist is one composed of an indefinite number of unconnected particles, revolving round the planet with different velocities according to their respective distances. These particles may be arranged in series of narrow rings, or they may move through each other irregularly. In the former case the destruction of the system will be very slow; in the second case it will be more rapid, but there may be a tendency towards an arrangement in narrow rings, which may retard the process." It follows from Maxwell's theory that the inner ring must have a greater angular velocity than the outer ring; and that this is the fact was later shown by Keeler at the Allegheny Observatory.
Aberdeen was the meeting place of the British Association in 1859. William Rowan Hamilton was there, full of his new method of quaternions; also Tait, now professor of mathematics at Belfast, and a disciple of Hamilton's. Maxwell was introduced to Hamilton by Tait. He had doubtless already studied the new method, from which he assimilated many ideas which figure largely in his Treatise on Electricity and Magnetism. At Aberdeen there are two colleges, Marischel College and King's College, each of which had then a Faculty of Arts. An agitation for a change had been in progress for some years; in 1860 it ended in a fusion of the two faculties of arts. The Kings College professor of physics was David Thomson, of whom you doubtless have never heard, yet Thomson was retained, and the gifted Clerk Maxwell was left out. However the Crown gave him compensation in the form of a pension. Just then Forbes resigned the chair of physics at Edinburgh; the two friends Maxwell and Tait were rival candidates, and Tait was successful. The contest did not change their friendship. Maxwell was immediately appointed to the corresponding chair in King's College, London.
