on some of the leading Doctrines of Caloric, &c. 48 
phon under E is evidently superfluous, merely containing in its 
two legs a useless weight of equipoised mercury. Accordingly 
for high heats, the apparatus fig. 2, or 3, is employed, and 
the same method of procedure is adopted. The aperture at O, 
fig. 3, admits the bulb of the thermometer, which rests as usual 
onl”, The recurved part of the tube is filled with mercury, and 
then alittle liquid is passed through it to the sealed end. Heat 
is now applied by an Argand flame to the bottom of C, which is 
filled with oil or water, and the temperature is kept steadily-at. 
212° for some minutes. Then a few drops of quicksilver may 
require to be added to D” till L” and 2” be in the same _hori- 
zontal plane. The further conduct of the experiment differs 
in no respect from what has been already described. The liquid 
in C is progressively heated, and at each stage mercury is pro- 
gressively added over L” to restore the initial level, or volume at 
4”, by equipoising the progressive elasticity. The ‘column above 
L” being measured, Tepresents the succession of elastic forces. 
When this column is wished to extend very high, the verti-. 
cal tube requires to be placed for support in the groove of a 
iong wooden prism. 
The height of the column in some of my experiments being 
nearly 12 feet, it became necessary to employ a ladder to reach 
its top. 1 found it to be convenient in this case, after observing 
that the column of vapour had attained its primitive magni- 
tude, to note down the temperature with the altitude of the co- 
lumn; then immediately to pour in a measured quantity of 
mercury nearly equal to three vertical inches, and to wait till the 
slow progress of the heating again brought the vapour in equili- 
brio with this new pressure, which at first had pushed the mer- 
cury within the platina ring at 7”. When the lower surface of 
the mercury was again a pangens to this ring, the temperature 
and altitude were both instantly observed. , 
This mode of conducting the process wi!l account for the ex- 
perimental temperatures being very often odd and fiactional 
numbers. I present them to the public as they were recorded 
on the instant in that particular repetition of the experiment 
which I consider most entitled to confidence, To trim and 
fashion the results into an orderly-looking series, would have 
been an casy task ; but in my opinion this isa species of decep- 
tion very injurious to the cause of science, and a deviation from 
the rigid truth of observation, which ought never to be made for 
any hypothesis. ° We shall afterwards have ample opportunities 
of exposing the fallacy of such premature geometrical refine- 
ments. 
The thermometers were constructed by Creighton, with his 
well- known nicety, and the divisions were read “off with a lens, 
SO 
’ 
