42 
Miscellaneous Notices. 
5 On the Determination of the Mean Temperature of the yfm—Thia subject 
has been investigated by M. G. G Hallsueem, who gives the following algebra.c 
formula, which correctly repiesents the mean temperature for all h,urope. 
;Ti + 0.33 + 0.41 sin [(» _ 1) 30“ + 124” 8')] 
v = mean temperature. 
n = the ordinal number of the month for which the temperature is to be calculated 
(thus, for March, n = 3). 
| ( x f + x e) = the mean temperature taken as the mean of observations taken 
at ten o’clock in the morning and evening. ... 
In winter \ ( xf 4 - * e ) = v very nearly ; whilst, in summer, this quantity is , of 
a degree greater than v at Paris, Halle, and Abo.— Anual. der. Phys. und Chem. 
1825, />. 373. 
6 On the Barometer — The following are conclusions at which M. Bohnenberger 
has arrived relative to the barometer. 1st, The surface of mercury in a tube 14-5 
lines in diameter, is slightly rounded at the edge; but, at the distance of two lines 
from the glass, capillary depression disappears, and the surface is level. 2d, Ihe 
mercury in a tube 5.8 lines in diameter, is convex over the whole surface, the de- 
pression being .035 of a line- 3d, The depression is generally less in a vacuum 
than in the air, so that a syphon barometer gives results too high, and the more so 
as the tube is smaller. 4th, Barometers constructed with tubes five lines in diame- 
ter, do not require tapping to cause them to assume their proper height ; and 
comparatively slight blows easily make the mercury rise too high in tubes of a 
smaller diameter — Annul. der Phys . und Chem. 
7 — Heat evolved from Air by Compression By a mathematical investigation 
of the heat extricated from air, when it undergoes a given condensation, and by a 
reference to the experiments of Clement, Gay Ltissac, and others, Mr. Ivory finds, 
that the heat extricated from air, when it undergoes u given condensation , is equal 
to three-eighths of the diminution of temperature required to produce the same 
condensation , the pressure being constant ” Air, under a constant pressure, dimi 
nishes 1.480th of its volume*, for every degree of depression on Fahrenheit’* 
scale ; and therefore one degree of heat will he extricated from air, when it under- 
goes a condensation equal to X §= T | C . ^ a mass of air were suddenly reduc- 
ed to half its bulk, the heat evolved would be | -f- — 90° Phil. Mag . N» 
S. i. 89. 8 
8 .-—.Specific Gravities , fyc. of Vapour. — The following table is from Mr. Tred- 
gold's work on the steam engine. 
Substance. 
Specific 
gravity 
in liquid 
state, wa- 
ter being 
unity. 
Specific 
gravity 
in va- 
pour, air 
being 
unity. 
Volume 
of vapour 
for one of 
liquid at 
00°, and 
30 in. 
mercury. 
I 
Constant Volume 
No- for at the 
formula, boiling 
point of 
;the li- 
quid. 
1 
Boil- 
ing 
point. 
(Fah.) 
Water 
Alcohol 
Sulphuric ether 
Sulphuret of carbon 
Naphtha 
Oil of turpentine 
Oil-gas liquid 
1000 
•825 
•632 
1 272 
•758 
•792 
•850 
0 625 
1- 6133 
2 580 
3 6447 
2 833 
5013 
2- 700 
1324 
422 
2113 
39 4 
224 
130 
260 
76.5 
24.5 
117. 
23 
13 
7-5 
15 
1711 
476 
220 
440 
280 
193 
837 
212“ 
173° 
104“ 
116° 
186° 
316° 
186” 
At 32° F. 
Rep. Pat . Inv. vi. 109. 
