650 
PHYSICS: A. G. WEBSTER 
Proc. N. a. S. 
The new methods here described consist, first, in the use of new experi- 
mental methods for obtaining the pressure in the gun, the position of the 
shot, and the muzzle velocity; second, in making the theory depend upon 
a new differential equation, and third, in the use of the graphic methods 
of calculation and integration that are common in engineering problems. 
The experimental methods hitherto have depended on the crusher gauge 
of Sir Andrew Noble and the Le Boulenge chronograph, both almost 
unchanged since their invention fifty years ago, and both giving but a 
single value of the pressure or the velocity. To be sure the Sebert veloci- 
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meter gives a continuous record of the position of the shot as a function of 
the time. It will readily be seen how a continuous record, with an infinity 
of values of the pressure, as well as a more direct measure of the positions 
of the shot, will increase our knowledge of the whole process. 
We must first decide upon the equation of state that is to be used for 
the gases generated by the explosion. It has been shown in a previous 
paper in these ProckKdings (Vol. 5, pp. 286-288, July 1919) what equations 
of state are compatible with the constancy of the difference of specific 
heats at constant pressure and constant volume, and we shall use the 
equation of Clausius, 
