WAS TUB FORCES. 297 



trary, 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 suc- 

 ceeded 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 resume of the well-substantiated 

 results of scientific research applied to the subject. The French phys- 

 icist 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 me- 

 chanical force, to raise 2,247 billions X 774 pounds to the height of 

 one foot. To come down to figures that are less difficult of concep- 

 tion, 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 ex- 

 pended 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 atten- 

 tion 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^- 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^ 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 actu- 

 ally put into practice in the production of an engine that runs with 

 great uniformity at a speed of 240 revolutions per minute, and con- 

 suming at this rate only part of the steam made by the solar generator 

 employed. From the very brief and imperfect accounts that have 



