158 Intelligence and Miscellaneous Articles. 
have transferred to the November Number of your Journal, consisted 
in first bringing the observed pressures to what they would be at 
the neutral point of temperature, applying next the correction for 
capacity, then bringing the resulting barometric heights to what they 
would be at 32°, and lastly adding the corrections for capillarity. 
There is, I need not say, nothing peculiar in this process. Not 
having by me the portable barometer (one by Newman) which I 
used in my experiments, I cannot exactly state the neutral points of 
pressure and temperature, and the corrections for capacity and capil- 
larity peculiar to it, and which are, as usual, engraved upon its 
mounting. I may mention, however, that the coefficient of mer- 
curial expansion for one degree Fahrenheit which I have employed 
in the reductions is ‘0001 ; the number very nearly which results 
from the well-known experiments of Dulong and Petit. I appre- 
hend that Mr. Moyle has been led into error by supposing me to have 
used a syphon barometer with moveable scales, an instrument whose 
indications require to be corrected for temperature alone. 
Iam, Gentlemen, your obedient Servant, 
28 S. Baggott-Street, Jan. 16, 1843. ’ James APJOHN. 
ON THE EXTRAORDINARY DEPRESSION OF THE BAROMETER ON 
JANUARY 13TH, 1843. BY H. H. WATSON, ESQ. 
To the Editors of the Philosophical Magazine and Journal. 
GENTLEMEN, 
The very extraordinary depression of the barometer which oc- 
curred yesterday, will doubtless have been noted by many of your 
readers ; and probably the subjoined account of the observations made 
by me, at this town, on the height of the mercurial column, will not 
be unacceptable for publication in your Journal; as, by comparison 
with the notes made by distant observers, they may assist in showing 
how far the depression has been general. 
Height of the Height of the 
13th Jan. 1843. Mercurial column. 13th Jan. 1843. Mercurial column. 
9 A.M. 27°81 inch.|| Half-past 3 P.M. 27°81 in. 
10 a.m. 777 4 pM. 27°85 ... 
Half-past 10 a.m. 27°75... || Half-past 4 p.m. D087 "igs 
11 a.m. Dy ark Maen 5 P.M. 27°87.4.0, 
Half-past 11 a.m. 27:72 ... || Half-past 5 p.m. Pa bare Mees 
12 PY lon! halla 6 P.M. 27°88... 
Half-past 12 p.m.' 27°72... 7 P.M. 27°94 ... 
1 rem. Dd ET Bv-vinne 8 P.M. DALE w2- 
Half-past 1 P.M. Py: en 9 P.M. 28°01 ... 
2 P.M. Ce kek re 10 p.m. 28°03 ... 
Half-past 2 P.M. Wiehe kes Il p.m, 28°04 ... 
3 P.M. \ ev ee 
The greatest depression was from half-past 11 a.m, to half-past 12; 
the height of the mercury then being 27°72 inches. The mean annual 
height of the barometer at this town, as obtained from my observa- 
tions made morning, noon, and night during twelve years, com- 
