182 



GREENHOUSES 



Temperature Temperature Comparative 



Cent. Fahr. Volume 



4 39.1 1.00000 



10 50. 1.00025 



20 68. 1.00171 



30 86. '....1.00425 



40 104. 1.00767 



50 .122. ...1.01186 



60 140. 1.01678 



70 158. 1.02241 



80 176. . 1.02872 



90 194. 1.03570 



100.. ..212. .. ..1.04332 



From the above table it will be seen that 

 the increase in volume from 50 to 212 de- 



U U 



<u 



I 



1 





Fig. 97. Automatic expansion tank. This is con- 

 nected with the city water system and will auto- 

 matically keep the heating system filled. See also 

 G, Fig. 94 



