find many substances which are apparently identical in composition, but which possess diverse qualities. Certain conditions are requisite to produce different states of the same compound. If these conditions are not fulfilled, the required combination is not made. With the cannibal our equation of the conservation of force would require a small term to represent the mind and soul, but a comparatively large one, it may be, to account for that stress of the particles, so to speak, which manifests itself as life. The source of the physical energy is the sun's heat. Looking, therefore, at the problem of life and mind from a purely scientific point of view, we seem to require a source from which can come the principle of life, and which can create moral and intellectual growth in suitable soil and under fitting conditions. In the case of the energy derived from the sun's heat we have a cycle of operations in which there is no annihilation of force. If we grant that there is a source of life and mind independent of mere chemical change produced by the sun's heat, and if we adhere to the notion of the conservation of force applied to this principle of life and mind, we are led to adopt the idea of a cycle of operations in which there is no annihilation of spiritual force. The doctrine of the existence of the spirit after physical death seems to me not to be foreign to the scientific ideas of the conservation of force, which have now obtained such complete supremacy in the science of physics; or to the doctrines of Darwin, which are accepted by so large a body of eminent naturalists. Without the sun there would be an annihilation of force. When energy is dissipated, we find the sun exalting it again by processes which we cannot completely follow. The idea of a great source of life and mind, the prototype of our physical sun, which sets in motion a vast scheme for the survival of the fittest, and the exaltation of energy in vast cycles, is not inconsistent with the doctrine of the New Testament, and seems to be required in a philosophical theory which shall endeavor to account for the differences in that great spiritual world which are continually suggested to the human mind by the various types of mental growth.
| THE FIRST POPULAR SCIENTIFIC TREATISE. |
By Professor S. P. LANGLEY,
OF THE ALLEGHENY OBSERVATORY.
SOME one has said that there is nothing in all the world of common places which was not once a novelty, and born from the conception of an original mind. The idea that science is not for the professional student only, but that every one will take an interest in Us results if they are only put before the world in the right way—this notion which has now produced a literature of its own—even
