Page:Popular Science Monthly Volume 15.djvu/311

, has seriously occupied the attention of such eminent practical engineers and mechanics as Ericsson, and others scarcely less widely and favorably known; and, although up to the present time nothing very tangible has resulted from their labors, they have at least succeeded in demonstrating, beyond reasonable doubt, that the problem is susceptible of practical solution.

To convey some adequate notion of the incalculable floods of power that await the bidding of the compelling genius of invention, I will invite your attention to a very brief résumé of the well-substantiated results of scientific research applied to the subject. The French physicist Pouillet, with the aid of elaborately refined apparatus, estimated that the earth receives from the sun in each and every minute 2,247 billions of units of heat—a quantity sufficient, if converted into mechanical force, to raise 2,247 billions &times; 774 pounds to the height of one foot. To come down to figures that are less difficult of conception, let us confine our attention to that part of the solar heat that falls upon the oceans, and to the fraction of that portion which is expended in the work of evaporating the water.

Without entering into an explanation of the modes in which the following calculations have been made, and which would run into far greater length than the limited time at my disposal this evening would warrant, I will simply give you the results.

I have said, you will remember, that we would confine our attention to that portion of the solar heat that falls upon the oceans, and to that fraction of it which is expended in the work of evaporating the water; in doing which alone, the sun raises during every minute an average of not less than 2,000,000,000 tons of water to a height of 3$1⁄2$ miles—the mean altitude of the clouds. To express this prodigious exercise of power in more familiar form, I may put it this way, that to continuously raise this weight of water to the height of 3$1⁄2$ miles per minute would require the continuous exercise of the force of 2,757,000,000,000 horses per minute.

Here, then, is power enough to satisfy the most enthusiastic inventor, and leave him plenty of margin; and if the believers in the sun-engine shall ever succeed in giving mechanical expression to but the merest fraction of this superabundance, they may safely count upon creating as profound a revolution in the world of industry as that which was ushered in with the steam-engine.

Ericsson, who has devoted much study to this enticing problem, has announced his unqualified belief that the sun-engine is practicable. He has progressed so far as to lay down the general principles on which he proposes to construct such a motor, and which he has actually put into practice in the production of an engine that runs with great uniformity at a speed of 240 revolutions per minute, and consuming at this rate only part of the steam made by the solar generator employed. From the very brief and imperfect accounts that have