“The spectroscopic results fail to give conclusive evidence on this point; still, perhaps, upon the whole, especially if we consider the photographs of last year, the teachings of the spectroscope are in favor of the view that the self-light of comets is due to electric discharges. Those who are disposed to believe that the truth lies in this direction, differ from each other in the precise modes in which they would apply the known laws of electric action to the phenomena of comets. Broadly, the different applications of principles of electricity which have been suggested, group themselves about the common idea, that great electrical disturbances are set up by the sun’s action in connection with the vaporization of some of the matter of the nucleus, and that the tail is probably matter carried away, possibly in connection with electric discharges, under an electrical influence of repulsion exerted by the sun. This view necessitates the supposition that the sun is strongly electrified, either negatively or positively, and further, that in the processes taking place in the comet, either of vaporization or of some other kind, the matter thrown out by the nucleus has become strongly electrified in the same way as the sun—that is, negatively if the sun’s electricity is negative, or positively if the sun’s is positive. The enormous disturbances which the spectroscope shows to be always at work in the sun must be accompanied by electrical changes of equal magnitude, but we know nothing as to how far these are all, or the great majority of them, in one direction, so as to cause the sun to maintain permanently a high electrical state, whether positive or negative.” Unless some such state of things exist, Sir John Herschel’s statement, “That this force” (the repulsive force forming the tail) “can not be of the nature of electric or magnetic forces,” must be accepted, for, as he points out, “the center of gravity of each particle would not be affected; the attraction on one of its sides would precisely equal the repulsion on the other.” Repulsion of the cometary matter would only take place if this matter, after it has been driven off from the nucleus and the sun, have both high electric potentials of the same kind. Further, it is suggested that luminous jets, streams, halos, and envelopes belong to the same order of phenomena as the aurora, the electrical brush, and the stratified discharges of exhausted tubes.