OF COAL AND RATE OF EVAPORATION. 27. 
Fire-place 5 feet 1 inch by 6 feet 11 inch=35.1 square 
feet of fire surface. 
Fire-bars placed 14 inches from the bottom of the boiler 
at the front, half inch thick with half inch spaces. 
Boiler plate 35;t8s of an inch thick. 
Flame-bed, which was carried up to near the water 
mark, 6 inches from the bottom of boiler. 
No return flue. 
Water evaporated from 60° by one pound of coal. 
Ib 
When worked with the fire-bars 12 inches from the ss 
bottom of the boiler, the yield was ....... ee 6.14: 
With an arrangement to cause the draught to 
impinge against the boiler bottom................. 6.30 
By lowering the bars 2 inches, and under ordinary 
Cee ats) 121 72): Ee er ea a 6.46 
By the introduction of a series of half-bridges, 
whereby the draught was dispersed and caused 
fa impinge im all. directions,....6. ,.../2Psias ce vaie-as 6.69 
By lowering the bars 114 inches more (whole dis- 
tance 254 inches), under ordinary circumstances 5.11 
This boiler had been fitted up previously to these expe- 
riments, and worked for some time as seen in Fig. 14. 
