1896-97.] J. R. Erskine Murray on a, New Thermometer. 299 
On a New Form of Constant Volume Air Thermometer, 
which shows the Total Pressure directly, and may 
be graduated in degrees by Temperature. By J. R. 
Erskine Murray, Assistant-Professor of Electrical Engineer- 
ing and Physics in the Heriot-Watt College, Edinburgh. 
(Read March 15, 1S97.) 
§ 1. The thermometer described in the present communication is 
a constant volume one. Its advantages proceed mainly from a 
simple arrangement whereby the total pressure of the enclosed 
air, and hence its temperature, since these are proportional, is 
FIG I 
measured directly by the height of one column of mercury. The 
external atmospheric pressure is eliminated by the adjustment of 
an auxiliary reservoir of mercury. 
§ 2. In fig. 1, A is the air-bulb, B is the pressure-gauge, which is 
an ordinary barometer tube with a vacuum above the mercury 
