426 
LORD RAYLEIGH ON THE LAW OF THE PRESSURE OF GASES 
1. 
Yi 
01 
Vs 
■J"! 
Vo 
h 
11. 
Y.2 
e.-, 
Vs 
To 
V 4 
T 2 
HI. 
_ 
Vs 
T3 
Yg' 
tz 
lY. 
— 
Vs 
Vf 
"4 
Ill the first observation is the volume of the two large bulbs and 6-^ the 
temperature of the water-bath, reckoned from some convenient neighbouring 
temperature as a standard. Vg is the ungauged volume ab’eady discussed whose 
temperature is given by the upper thermometer. Vg is the (larger) volume in the 
side apparatus whose temjierature b is that of the lower thermometer. In the 
second observation Yo is the volume of the upper bulb and 6^ its temperature. Y^ is 
the volume in the side apparatus whose temperature, as well as that of Yg, is taken 
to be To, the mean reading of the upper thermometer. III. and lY. represent the 
corresponding observations in which the large bulbs are not filled. The reading of 
the water-bath thermometer is in every case denoted by 6, that of the upper 
thermometer by r, and that of the lower thermometer by t. The temperature of the 
columns of mercury in the manometers is also represented by r. 
As an example of the actual quantities, the observations on air between October 28 
and November 5 may be cited. The values of Y^^ and Yg are approximate. As 
appears from the formulse, Yg occurs with a small coefficient, as does also Y^, except 
in the ratio Y^ : Yg otherwise jirovided for. We have 
Yi = 258-4, Yg^lD-Oo; 
Y^ = -810, Yg = 20-493; 
Y,-Y/= -0841, Yg - Yg'= -0266 ; 
e^= - -077, - -059 ; b = ’257, b = -141 ; 
Tj = -092, To = -]86, "^3 — — "033, = -100. 
The volumes are in cubic centimetres and the temperatures are in Centigrade 
degrees reckoned from 14°. 
An effort was made, and usually with success, to keep all the temperature 
differences small, and especially the difference between 6^ and ^g. It is desirable 
also so to adjust the c[uantities of gas in the two cases that Y^, — Y/, Yg — Yg' shall 
be small. 
The Reductions. 
The simple theory has already been stated, but the actual reductions are rather 
troublesome on account of the numerous temperature corrections. These, however, 
are but small. 
We have first to deal with the expansion of mercury in the manometers. If, as in 
