OF THE CRITICAL VELOCITY OF WATER AVITH TEMPERATURE. 
51 
consistent results, but after many trials this was accomplished. A disturhing cause, 
which could not be altogether avoided, was the rise or fall of the temperature of the 
water as it flowed along the pipe ; a fall if the temperature of the room was above 
the temperature of the water, and vice vevsd. This was partly removed by coverino' 
the pipe with thick cotton-wool lagging overlaid with flannel, and in order to obtain 
a mean value of the temperatui'e of the water in the pipe a long-stem thermometer 
was fixed in the tank and another was immersed in the outflowing water, and a mean 
value of these readings was taken as the true temperature in the pipe. 
Temp^^C 
60 
50 
40 
30 
00 
10 
0 
10 00 30 40 50 60 
Fig. .3. 
A plot of the variations obtained is shown in fig. 3, in which the line AB gives the 
temperature of the outflow water, CD the temperature of the tank, and EF the 
corresponding temperature of the room. The relation between the tank temperature 
and outflow temperature is shown to be jiracticafly a linear one, thereliy warranting 
the correction. 
In all, ten series of runs were made at temjieratures covering tlie range, and the 
results obtained are recorded in the following talile, and are shown on fig. I. 
H 2 
