ascending from the Sun's body, what changes of appearance are they likely to undergo in the neighbourhood of a cyclone? For some distance round a cyclone there will be a drawing in of the superficial gases toward the vortex. All the luminous spaces of more transparent cloud forming the adjacent photosphere, will be changed in shape by these centripetal currents. They will be greatly elongated; and there will so be produced that "thatch"-like aspect which the penumbra presents. * * * * * [The explanation of the solar spots above suggested, which was originally propounded in opposition to that of M. Faye, was eventually adopted by him in place of his own. In the _Comptes Rendus_ for 1867, Vol. LXIV., p. 404, he refers to the article in the _Reader_, partly reproduced above, and speaks of me as having been replied to in a previous note. Again in the _Comptes Rendus_ for 1872, Vol. LXXV., p. 1664, he recognizes the inadequacy of his hypothesis, saying:--"Il est certain que l'objection de M. Spencer, reproduit et développée par M. Kirchoff, est fondée jusqu'à un certain point; l'intérieur des taches, si ce sont des lacunes dans la photosphère, doit être froid relativement.... Il est donc impossible qu'elles proviennent d'éruptions ascendantes." He then proceeds to set forth the hypothesis that the spots are caused by the precipitation of vapour in the interiors of cyclones. But though, as above shown, he refers to the objection made in the foregoing essay to his original hypothesis, and recognizes its cogency, he does not say that the hypothesis which he thereupon substitutes is also to be found in the foregoing essay. Nor does he intimate this in the elaborate paper on the subject read before the French Association for the Advancement of Science, and published in the _Revue Scientifique_ for the 24th March 1883. The result is that the hypothesis is now currently ascribed to him.[26]