443 
We are thus compelled in strictness to omit that result alto- 
gether in deducing the final mean. Combining, therefore, the 
results of the first and third series, according to the method 
already laid down, we have 
m = .01140 ; 
a result which is identical with that of the third series, that 
of the first, (on account of its large probable error) not 
affecting the fifth place of decimals.* 
But the second series of experiments, though it cannot 
properly be combined with the others in deducing the mean, 
may yet serve another purpose. It may be made, in fact, 
a test of the accuracy of the different tables of the elastic 
force of vapour, within the range of temperature belonging 
to the experiments. With this view, the values of the co- 
efficient, m, have been calculated by Dr. Apjohn from his 
second series of experiments, by means of three separate 
tables of the elastic force of vapour. The first of these 
tables is that which has been employed above, as well as in 
his papers on the Wet Bulb Hygrometer in the Transactions 
of the Academy, and is that calculated by Dr. Anderson 
from the experiments of Dalton and Ure. The second 
table is that deduced by Mr. Kamtz, from his own experi- 
ments; and the third is that given in the Report of the 
Committee of Physics and Meteorology of the Royal Society, 
and calculated by Mr. Lubbock from a formula of his own. 
The results are given in the annexed table. 
* The errors of observation in the first series, which are so considerable in 
comparison with those of the other two, are manifestly owing to the mode of ob- 
serving f”. For it is obvious that the rapidly varying temperature of the thermo- 
meter in the condensation hygrometer cannot be noted ata precise instant, with 
the same certainty as that of a thermometer which has arrived at a stationary 
temperature. 
