A low power should be used at first, which may be changed for a somewhat higher one when the object has been found. But in no case will the use of really high magnifiers be found advisable. It is, of course, simply impossible with the tail, for which the naked eye is the best instrument, nor can the coma bear any degree of magnification, though occasionally the nucleus may be sufficiently sharply defined to bear moderate powers. The structure of the latter should be carefully observed, with particular attention to the question of whether any change can be seen in it, or whether there seem any tendency to such a multiplication of nuclei as characterized the great comet of 1882. It is possible that the pulses of vapour sunwards from the nucleus may also be observed. Appearance of motion, wavy or otherwise, in the tail, should also be looked for, and carefully watched if seen. Beyond this there is not very much that the ordinary observer can do; the determination of positions requires more elaborate appliances, and the spectroscope is necessary for any study of cometary constitution. It only remains to express a wish for the speedy advent of a worthy subject for operations. We turn now to those bodies which, as has been pointed out, appear to be the débris of comets which have exhausted their cometary destiny, and ceased to have a corporate existence. Everyone is familiar with the phenomenon known as a meteor, or shooting-star, and there are few clear nights on which an observer who is much in the open will not see one or more of these bodies. Generally they become visible in the form of a bright point of light which traverses in a straight line a longer or shorter path across the heavens, and then vanishes, sometimes leaving behind it for a second or two a faintly luminous train. The shooting-stars are of all degrees of brightness, from the extremely faint streaks which sometimes flash across the field of the telescope, up to brilliant objects, brighter than any of the planets or fixed stars, and sometimes lighting up the whole landscape with a light like that of the full moon. The prevailing opinion, down to a comparatively late date, was that shooting-stars were mere exhalations in the earth's atmosphere, arising as one author expressed it, 'from the fermentation of acid and alkaline bodies, which float in the atmosphere'; and it was also suggested by eminent astronomers that they were the products of terrestrial volcanoes, returning, after long wanderings, to their native home.