complete secondary operation has, however, absolutely no bearing on the conservative energy properties of the planet. In this respect, the system is perfectly balanced. Every transformation or absorption of rotatory energy, great or small, for long or short periods of time, is counteracted by a corresponding return. Absolute uniformity of planetary axial rotation is thus steadily maintained. It is scarcely necessary at this stage to point out that the verification of this description of natural operations lies simply and entirely in the observation of Nature's working at first hand. The description is based on no theory and obscured by no preconceived ideas, it is founded entirely on direct experimental evidence. The field of study and of verification is not restricted, but comprises the whole realm of natural phenomena. In a lifetime of observation the author has failed to discern a single contradictory phenomenon; every natural operation is in reality a direct confirmation. The conception of energy, working only through the medium of definite material machines with their incepting and limiting agencies, is one which is of great value not only in natural philosophy but also in practical life. By its means it is possible in many cases to co-ordinate phenomena, apparently antagonistic, but in reality only different phases of energy machines. It aids materially also in the obtaining of a true grasp of the inexorable principle of energy conservation and its application to natural conditions, and it emphasises the indefensible nature of such ideas as the radiation of energy into _space_.