MECHANICS AND USEFUL ARTS. G5 



Ericsson's communication to tlic pliilosophical faculty of Lunrl, 

 cannot fail to interest 3'oui* readers: 



*' • I have, of late years, spent much time and considerable 

 means on experiments to ascertain if the radiatino; heat of the 

 sun can bo concentrated in such a manner as to render it avaihible 

 for the production of motive power. 



** ' Sir John Herschers and Mr. Pouillet's experiments relating to 

 the radiating heat of the sun, altliough interesting, are not satis- 

 factory, as they deal only with low temperatures, showing how 

 much ice may be melted, or wiiat elevation of temperature of 

 water under the boiling-point may be ettected in a given time on 

 a given surface. The })urpose of my investigations and experi- 

 ments, on the other hand, has l^cen to ascertain what amount of 

 heat can be developed at the high temperature obtained by con- 

 centrating the solar rays, namely, bringing their power to bear 

 on a reduced surtace, and to devise the most efficient means for 

 eifecting such a concentraticni of the radiating heat. Apart from 

 these preparatory experiments, I have also, at the commencement 

 of the present year, constructed 3 different motors, which I term 

 solar engines. One of these is actuated by steam formed by the con- 

 centration of the heat of the solar ra3's, while the other 2 are actu- 

 ated by the expansive force of atmospheric air heated directly by 

 concentrated radiant heat. With reu'ard to the motive force itself, 

 1 have briefly to state that my experiujents show that, at the high 

 temperature requisite for steam engines and caloric engines, the 

 heating power of the sun on a surface 10 feet square Avill, although 

 in itself too feeble, evaporate on an average 489 cubic inclies of 

 water in the hour, by means of my mechanical contrivance for 

 effecting the necessary concentration. The importance of this 

 result cannot be overestimated when we reflect that such an 

 amount of evaporation demonstrates the presence of sufficient 

 heat to develop a force capable of lifting 35,000 pounds 1 foot liigh 

 in a minute, thus exceeding 1 horse-power. 



" ' The result of my experiments having established the fact that, 

 without an inconvenient extension of the mecJianism which I have 

 devised for concentrating the radiant heat, sufficient ))owercan be 

 obtained for practical purposes, it will now be proper to point out 

 what amount of mechanical power may be obtained by occupying 

 a Swedish square mile with solar engines. My several expei'i- 

 mcnts ha\ ino; shown that the concentration of the solar heat on 

 100 square feet of surface is more than sufficient to develop a 

 horse-power, it follows that 64,800 engines, each of 100 horse- 

 power, njay be kept in motion by the radiant heat of the sun on a 

 Swedish square mile. 



" ' It is true that the solar heat is often prevented from reaching 

 the earth. On the other hand, the skilful engineer knows many 

 ways of laying up a supply when the sky is clear and that great 

 storehouse is opened where the fuel may be obtained free of cost 

 and transportation. At the same time a great portion of our 

 planet enjoys perpetual sunshine. The field, therefore, awaiting 

 the application of the solar engine is almost bej'ond computation, 

 while the source of its power is boundless. 

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