Report of the Committee on Steam Boilers. 95 



EXHIBIT G. 



Calculation of the Log of the Allen Boiler, exhibited at the 

 Fair of the American Institute, November, 1871. 



Determination of the heat carried away by the condensing water dis- 

 charged from the tank during the twelve hours trial. 



L Units. 



To 1.30 p. m., 1056 cub. ft. @ 62£ lbs. = 66000 lbs. 



@ range of 120°.TFahr 7,966,200. 



To 10.30 p. m., 5480 cub. ft. @ 62£ lbs= 342,500 lbs. ' 



@ range of 106°.08 Fahr 36,332,400. 



To 11.35 p. m. 650 cub. ft. @ 62£ lbs. =40 ,625 lbs. 



@ range of 50°.5 Fahr 2,051,562.5 



(a) Total British thermal units 46,350,162.5 



Determination of heat carried off by evaporation at the surface of 



the tank. 



Units. 



1168.12 lbs. x 1008°.8 (latent heat at 152°.7 Fahr. = (b) 1,178,404.5 

 Determination of heat carried away by water of condensation. 



Units. 



39670 lbs. @ 17°.9S (range = 63°.4S-45°.5=(c) 713 266. 6 



Total heat derived from fuel, as determined above. 



Thermal units. 



46,350,162.5 + 1,178,404.5 + 713,266.6= 48,241,833.6 



Deduct four per cent of (a) for errors (leakage and 



meters) 1,854,006.5 



Final and corrected results 46 , 387 , 827 . 1 



British thermal units per lb. combustible, 46,387,827.1-^4527= 

 10,246.92. 



Equivalent evaporation of water, temperature 212° Fahr., atmos- 

 pheric pressure=10,246.92-v- 966.6=10.60 lbs. 



Apparent results. Real results. 



Water evaporated per lb. of coal .... ^^o.=7.38 Wrs Q "= ^ 38 

 Water evaporated per lb. of combus- 

 tible jm^^S.76 3£fruL=8.75 



