Page:Popular Science Monthly Volume 41.djvu/277

Rh, a two-hundredth, a five-hundredth, or even a thousandth part of the whole." Doppler had also, in 1841, suggested that on the same principle on which a sound should become sharper or flatter if there were an approach or a recession between the ear and the source of the sound would apply equally to light; and Fizeau, about eight years later, had pointed out the importance of considering the individual wave-lengths of which white light is composed. Prof. Huggins was not able to continue his observations of this feature till 1872, when, having devised a trustworthy apparatus, and enjoying favorable weather, he applied his method to fourteen stars which were found to have a motion of approach and twelve which appeared to be receding. He remarked upon these results that the velocities of recession or approach assigned to the several stars by him represented the whole of the motion in the line of sight existing between them and the sun. As we know that the sun is moving in space, a part of these observed velocities must be due to the solar motion. He had not attempted to make this correction, because, although the direction of the sun's motion seemed to be satisfactorily ascertained, the velocity with which it was advancing rested on suppositions more or less arbitrary. It would be observed that, speaking generally, the stars which the spectroscope showed to be moving from the earth were situated in a part of the heavens opposite to Hercules, toward which the sun was advancing; while the stars in the neighborhood of that region showed a motion of approach. There were some exceptions to this general statement; and there were some other considerations which appeared to show that the sun's motion in space is not the only, or even in all cases the chief, cause of the observed proper motions of the stars. There could be little doubt that in the observed stellar movements we have to do with two other independent motions, namely, a movement common to certain groups of stars, and a motion peculiar to each star.

Pertaining to other subjects than spectroscopic astronomy on which Prof. Huggins has written, we notice a communication to the Royal Society On the Function of the Sound-post, and on the Proportional Thickness of the Strings of the Violin. A curious letter from him in Nature, in 1873, relates the case of a family of dogs the members of which had inherited an antipathy to butchers' shops and butchers. Some of them could not be induced to pass by a butcher's shop; others showed great uneasiness in the presence of a butcher, although they could not see him; and one of them attacked a gentleman visiting his master, whose business was that of a butcher. In 1872 Dr. Huggins edited and annotated an edition of Schellen's Spectrum Analysis in its Application to Terrestrial Substances and the