The present theories of the transmission of light and sound; of the production of winds, and sun-spots, and of the method of development and dissemination of heat, are in point of fact, unphilosophical and incomprehensible. It is quite remarkable that in the present century, excelling as it does any period in the world's history in exact and reliable scientific knowledge, such unsatisfactory opinions should obtain. The failure is still more inexplicable when we reflect that these subjects are in importance the highest which can engage our attention as scientists. We have at the present time sufficient reliable data whereon to found satisfactory hypotheses. We have but to utilize the means which the true scientists of the century have so wonderfully developed, and with which they have so prodigally surrounded us, in order to complete the consummation of the great and crowning achievement in physical science. FOOTNOTES: [1] Appendix, p. 97. CHAPTER III. THE GREAT FORCES, THEIR CHARACTER AND OPERATIONS. I now ask, What is the intimate and inherent nature of those forces? Do they, or either of them, belong to the domain of the supernatural? Are they the products of some supreme force, or forces, heretofore unappreciated? The reply is clear and unquestionable. The supernatural must necessarily be a part of the Divine Essence, and consequently intangible. Not so the subjects of our inquiry. They are _natural products_, therefore, and _the result of the operation of some power commensurate with the stupendousness of their manifestations_. _Sunlight and Sun-heat._ In the forces, light, and heat, what immensity of power is represented! Strangely enough we have ever imagined these forces to be the unaided work of the sun, as though that luminary could be capable of sending forth in undiminished exuberance, such marvels of force, during all the ages, and remain itself unexhausted! _The Great Law of Conservation of Force._ But how speaks the law of conservation, that law most enduring, and most inexorable? According to the decrees of that law, whatever is received by the earth from the sun, an equivalent for the same must again be returned from the earth to the sun, to the uttermost fraction.[2] Such being the conditions, how may this retro-acting process that all analogy and the profoundest scientific axiom prove to be in constant operation--how, I ask, may this retro-acting process be explained? What equivalent may the earth give back as compensation for such enormous benefits, for such stupendous powers? The laws of conservation may not be violated: _the earth will respond_. _How are the Spheres constructed?_