Report of tee Committee on Steam Boilers. 93 



EXHIBIT L 



Calculation of the Log of the Lowe Boilers, exhibited at 

 toe Fair of the American Institute, November, 1871. 



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

 charged from the tank daring the twelve hours trial. 



Units. 



To 11.00 a. m., 439 cub. ft. @ 62£ lbs.=27,437.5 lbs. 



@ range of 114°.3 Fahr.= ; 3,136,102.25 



To 9.00 p. m., 6823 cub. ft. @ 62£ lbs. =426,437.5 lbs. 



@ range of 80°.9 Fahr.= 34,498,793.75 



To 9.45 p. m., 90 'cub. ft. @ 62£ lbs. = 5,625 lbs. @ 



range of 13°.7 Fahr.= 77,062.5 



(a) Total British thermal units 37,711 ,962 . 50 



Determination of heat carried off by evaporation at the surface of 



the tank. 



Units. 



676.8 lbs. xl022°.54 (latent heat at 131°.5Fahr. =(b). . 692,055.072 

 Determination of heat carried away by water of condensation. 



Units. 



34000 lbs. @ 9°.8 (range=54°.8-45°) = (c) 333,200 



Total heat derived from fuel, as determined above. 



Thermal nnits. 



37,711,962.5 + 692,055.072 + 333,200= 38,737,217.572 



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

 meters 1,508,478.5 



Final and corrected result 37, 228 , 739 . 072 



British thermal units per lb. combustible, 37,228,739.072-^-3705 = 

 10,048.24. 



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

 pheric pressure=10,048.24-=-966.6= 10.40 lbs. 



Total weight of water actually evaporated, by equation Hx—h 

 ( W—x ) = u, where 



iZ=heat transferred by each lb. of steam. 

 h =heat carried into tank by one lb. of water. 

 x =weight steam, in lbs. 

 W= total weight feed. 

 U= total quantity of heat. 

 1156.3ar+ 263.8 (34000-z)=37,228,739.072. 

 x =31663.35 lbs. steam. 

 W-x= 2336.65 lbs water. 



Apparent results. Real results. 



Water evaporated per lb. of coal. . 3 4 y o ° ? =7.6S 31 ||oo 35 = 7- 2(> 

 "Water evaporated per lb. of com- 

 bustible ^0^ = 9.12 31663-3 5^3.55 



