course—the “Waste Forces of Nature,” to which I now invite your attention.
Of these, the first to be named, from the magnitude of the possibilities that advanced thinkers have attached to it, is that fountain of all terrestrial energy, our sun.
To introduce this topic properly, I beg to remind you at the outset that the progress of science during the last half century has been most pronounced and satisfactory in the investigation of the nature, origin, interdependence, and interconvertibility of the various manifestations of energy that are called familiarly “the forces of nature”; and among the most philosophical generalizations that the science of our times may boast of having established is the demonstration, upon the most complete and satisfactory experimental evidence, that every manifestation of terrestrial activity has more or less directly a solar origin. Every exhibition of force, physical or chemical, inorganic or vital, the multifarious consequences connected with the circulation of air and water over the surface of the earth, and in her oceans, and which involve the causation of the winds, aerial and aqueous currents, and rainfall, and the effects of these commonplace but vastly important phenomena in establishing and maintaining those climatic conditions upon which the existence of life upon the earth is absolutely dependent, are directly referable to the forces of solar radiation. Ay, there is good reason for the belief, which is entertained by most competent and eminent authorities, that the periodical recurrence of famines and pestilences and other scourges that afflict mankind, and which the superstitious of all ages are wont to ascribe to the anger of an offended deity, coincides with the periodical maxima and minima in the intensity of the solar emanations that reach the earth; and that even such apparently disconnected and arbitrary things as the social and political affairs of mankind, which are intimately bound up with the successful pursuit of agriculture and commerce, are therefore demonstrably under the direct and immediate dominion of the solar rays.
But, to return from a digression that is only of incidental interest to us here, I desire you to conceive of the amazing fact that the stupendous aggregate of terrestrial activity is derived from that infinitesimal fraction only of the solar emanations that is intercepted by the earth—a fraction less than the two-billionth part of the sum total of energy that he is unceasingly radiating into space; and it is my immediate purpose here to invite your attention to the interesting question whether it is within human reach to convert a portion of the measureless floods of power that the sun pours out upon the earth into mechanical energy, or into other forms in which it will be more directly available for useful purposes.
The proposition here announced, I must advise you, is not the visionary notion of impracticable theorists, but is one that, on the con-
