Units.
Heat of combustion................................... 2,828,200
" " evaporation of 26.08 lb. water............... -29,888
---------
Available heat of combustion.............. 2,798,312

Dividing by 238.25 lb. gives the heat per 1 lb.
of fuel used................................... = 11,745 units.
And temperature of furnace:
11,745 units/(18.125 lb. x 0.238) + 530 deg.......... = 3,253 deg.
Temperature of chimney 700 deg. + 460 deg................ = 1,160 deg.
Maximum duty (3,253 deg. - 1,160 deg.)/3,253 deg............. = 0.643 deg.

Work of displacing atmosphere by smoke at 700 deg.:
Cubic feet.
Volumes of gases at 70 deg......................... = 228.3
" " " " 700 deg......................... = 499.8
-----
Increase of volume.................... 271.5

Units.
Work done=
(194.46 lb. x 271.5 cub. ft. x 144 sq. in. x 15 lb.)
/722 units ..................................... = 147,720
Maximum amount of work to be expected =
3,248,425 x 0.643.............................. = 2,101,700
Deduct work of displacing atmosphere............. = 147,720
---------
Available work........................ 1,953,980

Actual work done:
Units.
1,620 lb. of water raised from 60 deg. and turned
into steam at 53 lb..... ...................... = 1,855,900
Loss by radiation and convection................. 70,430
10-1/2 lb. ashes left, say at 500 deg................ 1,129
---------
Total work actually done.............. 1,927,459
Unaccounted for.................................. 26,521
---------
Calculated available work........................ 1,953,980

The unaccounted-for work, therefore, amounts to only 11/2 per cent.
of the calculated available work.

Si