MISCELLANEOUS SUBJECTS 



generate high-pressure steam we can easily do this by 

 means of the sun's rays, even up to 500 Ib. to the square 

 inch. This, of course, would give us very high engine 

 efficiencies; but, on the other hand, we would lose much 

 more than we gained because, on account of the higher 

 temperatures of the boilers, the loss by conduction and 

 convection into the atmosphere would greatly increase. 

 Also the cost of constructing the boilers owing to the 

 strength of metal required would greatly increase, and, 

 as stated before, the cost per foot-pound of energy 

 produced is the deciding factor. 



The steam is generated in the sun-heat absorbers, five 

 in number (each 13 ft. wide at the top and 204 ft. long), 

 which are parabolic troughs for catching the sun's 

 rays and throwing them upon the boilers swung at the 

 focal line. 



Each mirror is set at such an angle in relation to the 

 sun and the boiler that all the sun's rays falling on the 

 mirrors are thrown on to the boiler. This boiler being 

 painted a dull black absorbs these rays and turns them 

 into heat, which generates the low-pressure steam 

 referred to. 



The heat absorbers are placed about 25 ft. apart, so 

 that they will not shade each other when the sun is low 

 in the morning and afternoon. Their axes point north 

 and south, and they turn from east to west on their axes 

 to face the sun. 



The mirrors are set in a light steel framework, each 

 one at the proper angle to throw the light upon the boiler, 

 and consist of ordinary sheets of third quality thin window 

 glass silvered on the back, and the silvering protected 

 by proper means from the atmosphere. 



At the focal line of all the light rays there hangs in 

 the present plant a cast-iron boiler, which is tubular at 

 the top and flat at the bottom where the water space is. 

 This boiler is 15 in. high, and is hung on light rods in 

 such a manner that expansion and contraction will not 

 interfere with it. 



These heat absorbers are set on crescents which roll 

 in a system of small racks and pinions for turning the 

 sun heat absorbers from a low eastern aspect in the 

 morning to a low western aspect in the evening. 



