15 
Steam Engine, 
damped by the introduction of fresh cocJ, and the coals 
which have fallen from f towards c, are not so rapidly kin- 
dled as if introduced above the burning fuel : same time 
the smoke which arises from these newly-introduced coals, 
passes partly through the full-kindled coal and partly 
over, and in contact with the great heat of the burning 
fuel, and, meeting at the same time with the current of 
fresh air coming downwards, and tending also to drive 
the smoke still nearer to the bright kindled fuel, does in 
general completely inflame the smoke, and render it use- 
ful in adding to the heat of the furnace. Another end ob- 
tained by the stream of fresh air, is to keep in some mea- 
sure the great heat of the furnace from acting so violently 
on that part of the hopper which is nearest it, and mostly 
exposed to its heat, and liable to be damaged thereby, 
which it does by tlie continual current of fresh cool air 
that is in contact with those parts ; the construction of 
the furnace may be much varied ; but the chief improve- 
ments are, that the fuel in combustion is supplied with 
air by the foreside as well as by the bars, the hopper is 
placed in such a situation that the kindled or unkindled 
coal may in part fall to the foreside of the furnace 
above the bars, as the other fuel is pu sited backward in 
the furnace, and tlie admission of fresh air to pass over the 
burning fuel by means of a definite space or spaces, open-, 
ing or openings, made for that purpose ; so that this 
stream, current, or currents of air, partly come in contact 
with the burning fuel itself, forcing also the smoke, with 
more immediate union with the burning fuel and great 
heat of the furnace. The Patentees do not pretend any 
claim to the admission of fresh air as a new principle, as 
they are sensible that this has been known long ago, and 
practised by admitting it at the furnace door, shutter, or 
mouth-piece, and at the opening where the coals are admits 
ted into the furnace ; their claim rests upon what has been 
