between the two men, and Glasgow seems to have become a favourite place of summer pilgrimage to Herschel. It was clear that he was favoured by the flowing tide of scientific thought. He took it at the flood: he even guided it into the channels along which it has since flowed in an ever increasing volume. It "is an arduous task," he said of this quest after our solar system's movement in space, "which we must not hope to see accomplished in a little time; but we are not to be discouraged from the attempt. Let us, at all events, endeavour to lay a good foundation for those who are to come after us." And this good foundation, by precept and example, he did lay.
With the boldness of a man who had confidence in himself and his instruments, he wrote: "I think we are no more authorised to suppose the sun at rest than we should be to deny the diurnal motion of the earth, except in this respect, that the proofs of the latter are very numerous, whereas the former rests only on a few, though capital testimonies." He founded this conclusion on a discussion of the motions observed in seven of the principal fixed stars. But in support of his view he also quoted a table of the proper motions of twelve stars in fifty years given by Lalande, motion in the two directions known to astronomers as right ascension and declination, corresponding to longitude and latitude on the earth. Twenty-seven motions altogether had to be accounted for. On the hypothesis of a general movement of the solar system through space, twenty-two out of these twenty-seven movements were explained. The live exceptions he "resolved into the real proper motion of the stars." He did not then know whether
