72 Count Rumford’s Account of a Method of 
with the intensity of the light of a given lamp, placed at a 
given distance, and burning with a flame of given dimensions, 
shall be known ; it will then be easy, from the known size and 
distance of the sun, to compute the relative density of his 
light at his surface, compared to the density of the light of 
the flame of the lamp at the surface of that flame. 
The intensity of the light emitted in the combustion of 
iron or of phosphorus in dephlogisticated air, as also that of 
all other burning, or red-hot bodies, may be compared and 
determined by this method with the greatest facility and 
exactness. 
In my next letter I shall endeavour to give you an account 
of the result of my inquiries with respect to the best and most 
oeconomical method of producing light by candles, lamps, &c. 
for common use ; together with a comparative view of the ex- 
pence of lights of various kinds, the quantity of light produced 
remaining the same ; with such further remarks and observa- 
tions as may occur. 
Munich, I am, &C. 
20th December, 1792. 
Letter II. 
DEAR SIR, 
Since my letter of the 20th December last I have made 
many improvements in the apparatus contrived for measuring 
the intensity of light, and I have now brought the principal 
instrument to such a degree of perfection, that, if I might 
without being suspected of affectation, I should dignify it with 
