---------
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 1½ per cent.
of the calculated available work.

Sir Frederick Bramwell ingeniously arranged his data in the form
of a balance sheet, and showed 253,979 units unaccounted for; but
if from this we deduct the work lost in displacing the air, the
unaccounted-for heat falls to less than 4 per cent. of the total
heat of combustion. These results show how extremely accurate the
observations must have been, and that the loss mainly arises from
convection and radiation from the boiler.]

The data necessary for our purpose are:

Steam pressure 80 lb. temperature 324° = 784° absolute.
Mean temperature of smoke 389° = 849° "
Water evaporated per 1 lb of coal, from and at 212° 11.83 lb.
Temperature of the air 60° = 520° absolute.
" of feed water 209° = 669° "
Heating surface 220 square feet.
Grate surface 3.29 feet.
Coal burnt per hour 41 lb.

The fuel used was a smokeless Welsh coal, from the Llangennech
colleries. It was analyzed by Mr. Snelus, of the Dowlais Ironworks,