718 Report of the Consulting Engineers on the Trials of 
only 1"67 lbs., and in engine No. 3113, 4*02 lbs. It is clear, 
therefore, that if 3125 had been worked with no greater excess 
than 3114, the 6*34 per cent, of loss of item 6 would have been 
reduced by 5*49 per cent., leaving only "85 per cent., — unless, 
indeed, there had been a set-off to be allowed for. 
With respect to this question of set-ofF, it will be seen that 
in the waste gases of 3114 there was 1*14 per cent, of carbonic 
oxide, while in 3125 there was no carbonic oxide whatever. 
Had there been in 3125 the same proportion of carbonic oxide 
as in 3114, the loss under this head would have amounted to 
126,100 units of heat, or about 4 per cent., so that the 6*34 
loss existing in the Balance-Sheet from excess of air would, — 
had 3125 been worked like 3114, — have been reduced by 2 per 
cent, only, the saving from not having an excess of air being, 
to the extent of 4 per cent., neutralised by the set-ofF due to 
allowing a portion of the carbon to escape in the incompletely 
consumed form of carbonic oxide. But great economy in the 
use of the air may be obtained without any carbonic oxide at 
all. For example, 3113, already quoted, while having an excess 
of only 4*02 lbs. of air (less than one-third of 3125), has no 
carbonic oxide whatever. 
The true way of obtaining a perfect adjustment of the air to 
the fuel to be burnt, so as to prevent excess on the one hand 
and carbonic oxide on the other, is to apply some mechanical 
means of firing, such as can be adapted so readily when liquid 
fuel is used, or when coal is reduced, as has been done by 
Mr. Crampton, to the state of powder. 
No doubt means exist, or may be devised, for feeding fuel in 
its ordinary form, so as to maintain a thoroughly regular fire— 
the essential condition for excellence of working. 
Referring again to the Balance-Sheet, we find that No. 8 
shows that in radiation and convection 9 '32 per cent, of the 
fuel was dissipated, and dissipated in a way that means 
inconvenience to those who are in the neighbourhood of the 
engine. 
It is not for us to suggest any particular kind of boiler- 
clothing composition, but we do call attention to the 'absolute 
need of efficient clothing on all parts of the engine and boiler, 
even of the front of the fire-box, so commonly left naked, 
although no doubt great care must be taken that the clothing at 
this part is not of such a nature as to become ignited. 
The loss under head 9, so far as regards that portion of it 
which was due to Unconsumed Fuel, arose simply from the 
stoppage of the trial at the end of a few hours, and would have 
formed a totally insignificant quantity in one extended to 24 
