90 Transactions of the American Institute. 



EXHIBIT F. 



Calculation of the Log of the Root 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 daring the twelve hoars trial. 



Units. 



To 9.30 p. m., 5332 cub. ft. @ 62^ lbs. =333,250 lbs. 



@ range of 97°.16 Fakr 32,378,570. 



To 10.25 p. m., 323 cub. ft. @ 62£ lbs. =20,187.5 lbs. 



@ range of 31°.06 Fahr 627,023.75 



(a) Total British thermal units 33 , 005 , 593 . 75 



Determination of heat carried away by evaporation at the surface 



of the tank. 



Units. 



710.94 lbs. x 1014°.7 (latent heat at 143°.l Fahr.)=(5) . . 721,390.818 

 Determination of heat carried away by water of condensation. 



Units. 



27896 lbs. @ 12°.37 (range=5S°.31-45°.94)=(c) 345,073.52 



Total heat derived from fuel, as determined above. 



Thermal units. 



33,005,593.75 + 121,390.818 + 345,073.52= 34,072,058.09 



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

 meters) . . 1,508,478.500 



Final and corrected result 32 , 751 , 834 . 34 



British thermal units per lb. combustible, 32,751, 834.34-f-3185. 5= 

 10,281.53. 



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

 pheric pressure=10,281.53-T-966.6=10.64 lbs. 



Apparent results. Real results. 



Water evaporated per lb. of coal .... -^^§-=7.34 ^ls^ -7.34 

 Water evaporated per lb. of combus- 



tihlp 2 78 9 6_ — O nil 2789 6 — fiW 



I1Dle 3 18 6.5 — °- ' ° 3186.$— °* ' ° 



