168 ARTIFICIAL ILLUMINATION. 
compared with a Pentane standard. The more common ordinary 
burner, No. 5 “‘ Bray,” being credited with only 1:5, you see that the 
Welsbach mantles are at least 8 times as efficient. 
The last item on the screen is an interesting one. ‘Treating the 
gas engine as a gas burner giving light through the means ofa dynamo 
and incandescent electric lamps, you see that the efficiency is 8 candle 
power for each cubic foot of gas burnt per hour in the engine. ‘Thus, 
if we reckon only the cost of the gas consumed in the cylinder, a gas 
engine isa more efficient light producer than any other gas burner 
except a Welsbach. 
(2.) The next table now on the screen shows you the result of 
tests to determine the comparative effects of an ordinary burner and 
the Welsbach as far as vitiation and heating of the atmosphere are 
concerned— 
VitiaTion or tan Arr anp Heat Herects. 
Actual Measurement after 1 hour in a room of 8200 cubic ft. capacity. 
ORDINARY BURNER WELSBACH 
Bray’s Special No. 6. INCANDESCENT 
@amadlewZower f ..uesc Mee ae cele 14 42 
(COMEMMYHMNOM 55 ccs 900 TA 3°2 
~~cubie ft. of gas per hour : 
Increase of Carbonic Acid Lee eae ices ~ 1591 8 
per 10,000 c. ft. of air : 
Ditto—per candle power... ... .. «.. 108 eg) 
Heating Effect (proportionate)... ...  ... 4 il 
per candle power... .... Theoretical 
IDO dge PACT Pose Rom iors coun one Mans 63 1 
per candle power... by actual measurement cae 
We may summarise the results by saying that, light for light, it 
shows that less carbonic acid is evolved from the Welsbach burner than 
from ordinary burners in the proportion of 1:9 to 10°8, or less than 1 to 
5. At the same time the heating effect of the Welsbach is shown, by 
actual measurement, to be less in the ratio of 1 to 6:3. 
Of course the heat evolved in any case must be exactly pro- 
portional to the quantity of gas actually consumed (although unfor- 
tunately this is not always understood) and therefore the comparative 
heating effects of the two systems of burners ought to have proved to 
be in the exact ratio of their consumptions. A practical test applied to 
the atmosphere of an ordinary room, however, would necessarily show 
some divergence from the true ratio on account of the virculation of 
the heated air and its passage to and from the outside of the room. 
The figures before you prove the Welsbach to be not only a brilliant 
light but a cool light, and it is also a far more healthy light than that 
obtained from ordinary gas burners. i 
(8.) The table on the screen to which I now direct your attention 
gives you the relative annual cost of producing a light of about 48 
