69 
fall in the discharging vessel during the discharges, this 
would cause a corresponding fall of temperature, which 
would again cause heat to flow from the metal vessel into 
the gas within. 
It is difficult therefore to say what the change of temper- 
ature was except in the extreme cases. With the experi- 
ments on the highest pressure, however, the times 7'5 
seconds, and the greatest possible falls of temperature 5*5° 
were so small that the communication of heat from the 
walls of the receiver would have been very slight, and hence 
we might expect that the discharges calculated on the 
assumption of no communication of heat would agree with 
the theoretical discharges multiplied by the real coefficient 
of contraction. This would be shown by an agreement in 
the successive coefficients obtained from the experiments 
with the higher pressures. On the other hand with the 
lowest pressures the times were so considerable, 170 seconds, 
and the greatest possible falls of temperature (assuming no 
conduction 94°) so great that the communication of heat 
would have been very great, and considering the compara- 
tively small mass to be heated (only one 13th of what it is 
in the highest experiments) might maintain the temperature 
approximately constant after falling some considerable 
amount below the initial temperature. In these last 
experiments, therefore, it would be expected that the 
discharge might be estimated as taking place at nearly 
constant temperature. 
The intermediate experiments would give intermediate 
results. 
According to this view for the high pressures since 
