Bredichin’s researches, showing that three distinct curvatures in comets’ tails correspond to the winnowing out by solar repulsive action of (1) hydrogen, (2) carbon, and (3) iron, seem worthy of careful study and investigation. It accords well with spectroscopic evidence as to the condition of the matter raised in gaseous form from the nucleus; and if as yet we have had no direct spectroscopic evidence of the existence of iron in comets, we know that meteors are closely connected with comets, and that many meteors contain iron. Moreover, as unexpected spectroscopic evidence of the presence of the substance sodium, common in so many meteors, has been found in the case of one comet, we may fairly hope that under yet more favorable conditions, the presence of iron also may be recognized in the same way. How far electricity may be looked to for an explanation of cometic phenomena, is a doubtful point among astronomers and physicists. For my own part, I must confess I share the strong objections which many physicists have expressed against the mere vague suggestion that perhaps _this_ is an electrical phenomenon, perhaps _that other feature_ is electrical too, perhaps _all or most_ of the phenomena of comets depend on electricity. It is so easy to make such suggestions, so difficult to obtain evidence in their favor having the slightest scientific value. Still, I hold the electrical idea to be well worth careful study. Whatever credit may hereafter be given to any electrical theory of comets, will be solely and entirely due to those who may help to establish it upon a basis of sound evidence—none whatever to the mere suggestion, which has been made time and again since it was first advanced by Fontenelle. Dr. Huggins says that he finds there is a rapidly growing feeling among physicists that both the inherent light (which he prefers to call the self-light) of comets and the phenomena of their tails belong to the order of electrical phenomena. An American astronomer recently wrote to him, as to American views of the self-light of comets, “I can not speak with authority for anyone but myself; still I think the prevailing impression amongst us is that this light is due to an electric, or, if I may coin the word, (far better not) an electric-oid action of some kind.” On this Dr. Huggins himself remarks: