Dr Fyfe on the Illuminating Power of Coal-Gas, &c. 233 
and narrower glass chimney is at the same time required. 
The advantages said to attend the use of this construction of 
burner, are, that an oil of inferior quality may be used, while 
at the same time the light is greatly increased. 
The solar lamp, containing solar oil, with a flame as high as 
could be got to be steady, and without smoke, was contrasted 
with the gas argand as before, burning three feet per hour. 
On comparing the lights, and taking the average of numerous 
trials, conducted at different distances, and when the wick 
was in different conditions, they were as 0.98 to 1; so very 
nearly equal that we may consider them as so. The oil, per 
gallon, costs 3s. 8d.; a pint was found to burn eight hours, or 
very nearly so, at a cost of 53d. The gas required for the 
same time is 24 or say 25 feet, which would cost 23d.; ac- 
cordingly the expense is rather more than twice, or say twice, 
that of the gas. 
To ascertain whether or not there is any saving by using 
the apparatus adapted to the solar lamp, the solar oil was con- 
sumed with a solar wick in the same argand with which the 
trials with the sperm and whale oils were made, and the light, 
as before, was contrasted with the argand, burning three feet 
per hour. The light and the consumpt of oil were found to be 
the same as with the other oils. The cost of the solar oil per 
pint is 54d., that of the whale oil 7d.; accordingly the expense 
is as the cost of the oils. It has been already stated, that by 
using the solar apparatus, the oil gave a light equal to that 
from an argand consuming three feet per hour, and that the 
pint of oil will last for eight hours ; the expense is therefore 
as 24d. to 53d., or say 1d to 2d. Now when the solar oil was 
burned in the common argand, and contrasted with the gas 
argand, the light wasas1to2.54. As the oil lasted for twelve 
hours, the cost of gas for that time would be 33d., or very 
nearly so. The comparative expense was therefore as 53d. x 
2.54 to 33d.; that is, as 3.98 to 1; whereas, by the solar lamp, 
it was only as 2 to 1; thus making a saving by the use of the 
solar lamp of nearly one-half of the expense. This peculiar 
construction of lamp is therefore a very great improvement ; 
for not only is there a saving in expense in the outlay for oil, 
