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DR. J. T. BOTTOMLEY AND MR. F. A. KING ON THERMAL 
explained; and, the temperatures corresponding to the times being known, the 
emissivities can be referred to their respective temperatures. 
29. Taking for an example the case of the results of April 2, 1906 (see table 
on p. 364, the times and the deflections (galvanometer readings) are given in 
Columns 1 and 3 ; and in Column 4 are given the logarithms of the deflections, 
while Column 5 contains the differences of these last, that is log v 0 — log v* Noticing 
that the difference of logarithms is a number which increases as the experiment 
proceeds, and is a function of the time, to deal with the numbers conveniently we 
assume 
log v 0 —log v — K t + 7l, 
% 
choosing K by inspection so that K£ shall contain the greater part of the number 
which expresses logi’ 0 — log v ; while n is a residue, as it were a correction on Kt, and 
obviously containing all the irregularities and the errors of experiment. 
* In the present investigation v 0 is the same as (v 0 - V), and v is the same as (v - V) of p. 358 ; that is, 
the present v 0 and v are the differences of temperatures, at times t 0 and t, between the cooling globe and 
the envelope. 
