16 MR. JOHN GRAHAM ON CONSUMPTION 
Eleventh Experiment.--- Draught good; thickness of fire 
5 inches. The coals in this experiment were fed upon the 
inner end of the fire-bars by a hole in the side of the 
brickwork, the red hot coals being pushed forward towards 
the front by the rake. 
Twelfth Experiment. — A repetition of the eleventh ex- 
periment, but with a slower draught and a thinner fire. 
III. Series or Experiments (SMALL BOILERS.) 
Fig. 4. 
SS E | 
4A Gr ZL oe 
to Feet. 
The next set of experiments was also made to ascertain 
the value of fiue space, but more attention was now 
given to the capacity of the hot air after it had passed from 
under the boiler to heat a separate boiler. The boiler used 
