to the oil consumed, than a larger one of the same form ; to 
illucidate this fact, I made the four following experiments : 
I had a small portable lamp made, with a wick composed 
of four flat wicks, touching each other in the Centre of a 
circle, in such a manner, as that a horizontal section of this 
compound wick, formed a cross at right angles. Each of 
these four flat wicks was three lines broad j and in adjust¬ 
ing the lamp for the first experiment, I cut each of these 
flat wicks in a slope, of such a degree as to leave the centre 
about a line higher than the circumference, and the four 
wicks only touched each other in the centre. 
These wicks being cut in this manner, it was easy to 
cause the lamp to burn with a very small flame, which was 
necessary to answer my intentions. 
I made four experiments with this lamp, and with the 
following results: 
Order of Ex¬ 
periments. 
Intensity of the light 
furnished by the lamp. 
Quantity of 
oil consumed 
per hour. 
Light furnished 
per hour, from the 
consumption of 
100 parts of oil. 
10 
25° 
67 
3 7 ° 
11 
100 
143 
70 
12 
225 
211 
112 
13 
255 
214 
118 
In the thirteenth experiment there was three times more 
light from a given quantity of oil than in the tenth. 
I made many other experiments, similar to these, with 
other lamps, and always with results analogous to those 
which we have seen ; but without stopping I pass on to other 
experiments made with candles, which have afforded the 
most interesting result. 
Exfi. 14.—To determine whether the delicate flame of a 
small candle gave less light than the flame of an ordinary 
candle, in proportion to the wax which it consumed, I made 
the following experiment: 
A small candle of the kind used in dark lanthorns, four 
lines and a half in diameter, was placed before the photo- 
U 
