PINE-APPLE BOTTOM HEAT. 



349 



more convenient, and afford a heat sufficient both in in 

 tensity and duration for any useful purpose. 



We have already shown how a system of tubes trans 

 mitting steam or hot water may be made available for the 



Fig. 46. 



production of bottom-heat. There is another method wor 

 thy of at least a cursory notice. Its invention is due to 



