I»K. M. AY. TRAVERS, MR. G. SEXIER, AXD DR. A. JAQUEROD 
1 IH 
11., The stem from the point alrearly referred to to the middle of the wall of the water 
space enclosing the barometer tnhe. The temperature of the stem was determined 
with sufficient accuracy hy means of a thei-mometer with the bulb placed between 
c and (■/. 
Volume = 0'103l cub. centim. 
In some of our earlier experiments, about 3 centims. of the stem outside the hypso- 
meter was enclosed het^^■een sheets of asbestos, and the temperature was determined 
hy means of a mercury thermometer. The mean temperature of this portion of the 
stem was usually about 90° Cf, and, as its volume was only 0 0182 cub. centim., its 
temperature could he taken as 100° (J. without affecting the value of Pj(^q. 
TIL The dead-space and remainder of the stem. The dead-space and barometer 
were enclosed in a v'ater jacket, as will be described presently; the temperature was 
determined hv means of the thermometer r. 
xJ 
Volume = [0-3904 -f 0-G3GA ffi 0-212 (0-125 - li)\, 
where A is the distance in centimetres between the point and the surface of the 
mercury, and h is the height of the meniscus. 
1 1. Ihe Manomatei' and its Connection, icith the Dead-Space, c£'c‘. 
T'he pressure on the gas in the thermometer was determined directly by observing 
the difference of the level of this mercury meniscus in the dead-space f and in a 
manometer g. By emplojdng this method it was necessary to take only two 
readings, and the obseived pi-essures were entirely independent of the atmospheric 
pressure. 
The tube/‘which formed the dead-space after removing the stop-cock was sealed 
at its lower end to a wider tube h, which was connected with the manometer tube g 
and with a tube which served to catch any air bubbles which might enter the 
apparatus through the stop-cock n and the rubber tube / leading to a mercury reservoir. 
A tube 5 millims. in diameter, sealed into the side of the tid:)e h, was connected to 
a stop-cock i of capillary bore, through which the gas coidd he introduced into tlie 
ap})aratus. Tlie tube Z- terminated above in a narrow glass tuT)e, connected by a piece 
of india.-ruhl)er pressure tubing with one liinl) of a glass stop-cock, through which 
traces of air entering through the tube / could be expelled. By closing the stop¬ 
cock n and compressing the rubber tube by the pinch-cock m the final adjustment of 
the level of the mercury in the dead-space could be effected. 
The manometer tube was carried vertically upwards from tlie bottom of h and 
bent above the level of the dead-space, so that its axis coincided witli that of the 
latter. In oliserving the pressure on the gas in the thermometer, it was only 
necessary to read the ditference of level between surfaces of the mercury in the dead- 
space and in the manometer tube which lav in the same vertical line, 'fhe top of the 
