210 
DR. H. T. BARNES ON THE CAPACITY FOR HEAT OF WATER 
view, taken from the ceiling. Corresponding parts ol the apparatus are indicated by 
the same letters in the two plates. 
Fig. 14, is taken looking towards the slate slab along one side of the laboratory on 
which the greater part of the apparatus was arranged. The water-motor A, which 
supplied the driving power for the circulation and all the stirrers, is seen on the 
extreme right. B is the heater, containing a centrifugal pump driven direct from 
the motor, which delivers the water into the regulator tank C (fig. 14) through a 
large rubber hose. Behind the tank is the hypsometer T, which was employed for 
pre-heating the distilled water at the higher temperatures, and the water-bath P, 
containing the tube resistances for regulating the flow of the distilled water. The 
distilled water reservoirs were on the floor above. D is the ebonite box containing; 
the standard resistances for current measurement immersed in oil with a stirrer 
driven by the central pulley (fig. 5). E is the copper water-jacket (fig. 11) containing 
the calorimeter, swathed in flannel, and connected by rubber hose on one side to the 
regulator tank C, and on the other to the circulating pump B. F is the switch-over 
Fig. 13. 
O 
tap (fig. 7) for delivering the flow into either of the two flasks G (fig. 8), and 
automatically recording the time of the switching over on the electric chronograph, 
the cylinder of which is marked Q in fig. 15. In the background of fig. 14, on 
the slate slab to the left are seen, H the Thomson-Varley slide-box, and K the 
100,000-olnn galvanometer. Nearer the middle at M is the 20-ohm galvanometer 
for the platinum thermometers. These are all beyond the range of fig. 15. L is the 
zigzag platinoid rheostat for regulating the main current so as to obtain the desired 
rise of temperature in each case. 
On the small table at the side in fig. 15 is seen the compensated resistance box Pi 
for the differential platinum thermometers, with small auxiliary boxes for current 
regulation. S is the rubber tube containing the leads to the heating lamp in the 
tank C. The relay, (fig. 14) worked by the regulator in the tank, and the shunt 
lamp are seen at Q in fig. 14, but are hidden by the jacket E in fig. 15. The Clark 
