HOW THE SUN WARMS THE EARTH ABBOT 



155 



and bottom by double air spaces. Each trough of the heater formed 

 a compartment. (The following six paragraphs are taken from the 

 paper cited in footnote 2.) 



The heater in the fourth phmt was in two sections, separated by a 

 footpath. The first section was covered by one layer of glass and 

 the second section with two layers. Both sections were inclined. The 



Water from ths distributing tank D. T. after flov/ing 

 through the glass-covered troughs H.H.H. absorbing 

 solar heat is stored in the storage tank S. T. This 

 hot water gives up its heat in the vaporizer V and 

 is sent back by the circulating pump C. P. to the 

 distributing tank. Single-headed arrows indicate the 

 flow of the water. Emergency steam boiler, B, for 

 cloudy tjeriods. 



Sulphur dioxide flows In the direction of the double- 

 headed arrows from the vaporizer coils to the engine 

 E. The exhaust vapor goes to the condenser C. 

 The liquid sulphur dioxide is returned by the feed 

 pump P. P. to the vaporizer. 



In practice the distributing tank is small; tho storage 

 tank S. T. holding both the hot and cold water. 



FiGUBK 4. — Diagrammatic plan of Willsie sun-power plant. 



heat-collecting liquid ran from the first section into the second sec- 

 tion, at a temperature of about 150° F., and from the second section 

 into tlie storage tank at about 180° F. These temperatures varied 

 with the time of day, wind, cloudiness, and other weather conditions, 

 and especially witli the amount of liquid flowing through the heater. 

 The solar-heated water was stored in a tank, insulated to prevent 

 the loss of heat by radiation. The heated water was then drawn 

 uniformly and continuously from the storage tank and made to give 



