central forces, but to trace the differentiation and transformation of material forms as determined by the differentiation and transformation of the formative energy of the universe. In this connection, observation and experiment have brought to light a number of the most significant facts, to one of which I may be permitted to draw attention before the conclusion of this paper. Force, or, more correctly speaking, energy, is not only indestructible, like mass; it not only passes through a cycle of transformations corresponding to the metamorphic round of physical forms; it is not only specialized at even pace with the specialization of its corresponding material structures; but, just as the progressive specialization of these material structures is, on the whole, an advance in the direction of greater definiteness and more perfect concretion (in the case of inorganic bodies, generally accompanied by greater condensation): so, also, the specialization of formative energy is, on the whole, characterized by an ever-increasing intensification. Generally speaking, the more advanced the stage of material concretion, the greater the intensity of its constitutive force. Faraday has somewhere observed that the chemical force contained in a drop of water, if transformed into heat and light, would be sufficient to illuminate the heavens. Of course, this intensification of force, in proportion to the condensation, concretion, and differentiation of the forms produced by it, is not a thickening of a substantive entity, but is simply an increasing complication in the relations in the establishment of which all realization consists. The energy which forms and maintains the higher and more definite forms of material existence has to overcome and to hold its own against not only the inherent energy of the primary physical form, but against the specialized energy of the intermediate forms as well.
I ought, perhaps, to observe here that, whenever energy is seemingly destructive, if is in reality reconstitutive of a conservative system of a lower grade.
But I must not be led into discussions which belong to special science, and are in strictness foreign to my theme; and, so far as I am at liberty to enter upon these discussions, especially in the field of chemical science, they must be reserved for another article.
| SKETCH OF DR. J. W. DRAPER. |
THE period from 1830 to 1870 is very strikingly marked in the history of science. It opens with great discoveries in electricity, and closes with very brilliant ones in light. Its middle portion is illustrated by the application of chemistry to physiology, which led to a revolution in the latter science, and indeed changed the face of
