processes of energy transmission at command, on which all our deductions must be based, does not warrant in the slightest degree the assumption of transmission between the sun and the earth. The most plausible of such assumptions is undoubtedly that which attributes transmission to heat radiation, but this has already been shown to be at variance with well-known facts. The question of light transmission will offer no difficulty if it be borne in mind that light is not in itself a form of energy, but merely a manifestation of energy as an incepting influence, which like other incepting influences of a similar nature, can readily operate across either vacuous or interplanetary space (§ 19). On these general considerations, deduced from the observation of terrestrial phenomena, allied with the conception of energy machines and separate masses in space, the author bases one aspect of the denial of energy transmission between celestial masses. The doctrine of transmission cannot be sustained in the face of legitimate scientific deduction from natural phenomena. In the later parts of this work, and from a more positive point of view, the denial is completely justified. 31. _Identification of Forms of Energy_ Before leaving the question of energy transmission, there are still one or two interesting features to be considered. Although energy, as already pointed out, is ever found associated with matter, this association does not, in itself, always furnish phenomena sufficient to distinguish the precise phase in which the energy may be manifested. Some means must, as a rule, be adopted to isolate and identify the various forms.