B. Silliman—Note to Stimpson's Paper. 377 
Art. XLIL—WNote on Mr. Stimpson’s Paper on Farmer's Theo- 
rem; by B. SULLIMAN. 
Mr. STIMPson’s criticism on the first experiment of my paper 
was induced by an obvious numerical error in the statement of 
the data, which Mr. S. has himself corrected in a foot note on 
p. 873. The experiment properly stated exactly sustains the 
theorem. 
I admit that in Experiment No. 2, the exponent comes nearer 
to the third power than to the square, being 2°689, 2°638 and 
2°669 ; in the three cases average 2°661. But it also indicates 
that the illuminating power of the standard 3-30 cubic feet was 
very imperfect. The experiments, however, appear to me to 
demonstrate clearly the radical inaccuracy of the old rule for 
photometric calculations, and that some ratio near to or greater 
the square gives often more trustworthy results than the 
old rule. 
Tn Experiment No. 3, the exponents are respectively 2552, 
2297 and 2-092, coming in the last very near the square. It 
shows that 4:88 cubic feet consumption gave the best results, 
and also that 3°72 and 7-219 cubic feet consumption gave very 
n. 
Mr. Stimpson rejects all the data given by me which are 
S doeratalion of the intensity of a rich gas 
1870. 
ay 
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