612 
DR. .T. T. BOTTOMLEY ON THERMAL 
Appendix. 
Added March, 1893. 
The method of calculation of the results of my experiments is explained in the 
body of my paper; but it has been suggested that a more detailed account of the 
calculations, with, perhaps, a numerical example, might be of value. Accordingly, 
though I fear it cannot be done without considerable repetition, 1 beg to supply the 
want in this appendix. 
The numerical results of my experiments are obtained, as has been explained, in 
the form of readings of the galvanometer deflection taken at equal intervals of time, 
five minutes being the interval most commonly adopted. The arrangements for 
making the observations at the precise instant are explained on p. 599 of the paper. 
These arrangements were perfectly successful. Thanks lai’gely to the skill of 
Mr. Tanakadate in this kind of observation, it was very rarely that a reading was 
missed; and when by any chance a reading was missed the failure was known and 
the exact time of the next observation was noted. There was on no occasion what¬ 
ever any uncertainty. 
At suitable times also the temperature of the surrounding vessel, and the state of 
the vacuum and other particulars, Avere noted. 
While an experiment on the cooling of a globe was in progress the galvanometer 
readings were plotted on to a laig-e sheet of squared paper. This Avas done because 
it Avas impossible to see into the enclosure; and some check Avas Avanted by which it 
could be known that everything was proceeding satisfactorily and had been carried 
out properly in the preparations for the experiment. Usually each experiment had 
some special feature for Avhich special preparation AA-as made ; and it Avas quite possible 
that some contact of the Avires of the thermo-junction, or some flaAv in the last solder- 
ino’ of the halves of the enclosure, should make the result of the lono- course of AA’aiting 
and observing valueless. Fortunately no such mischance did occur; but a check AA’as 
necessary, and the plotting of the curve, Avhich could be quickly compared by eye Avith 
others of the same kind, aftbrded a test Avhich AA^as particularly easy and satisfactory. 
The folloAving is a copy of one of the pages of my note-book. It explains itself; 
as. Indeed, each page ought to do :— 
