BOILERS, FUELS AND FLUES 213 



facturers, however, rate their boilers show- 

 ing their capacity. Some give the number 

 of square feet of glass that they will heat to 

 a given temperature; others give the number 



Fig. 112. Sectional view of boiler shown in Fig. Ill 



of linear feet of radiating pipe of a given 

 size which they will supply; and still others, 

 especially the manufacturers of large tubu- 

 lar boilers, give the capacity of their boilers 

 in terms of horse-power. 



Since different manufacturers often ques- 

 tion the correctness of the ratings of their 



