W. W. JSacques— Velocity of very Loud Sounds. 119 
velocity of sound was less than at a distance, but that 
going further and further from the cannon, the velocity of sound 
rosé lo a maximum considerably above the ordinary velocity and 
then fell gradually to about the velocity usually received. 
In order to determine whether the first low velocities were 
ue, as was supposed, to the retarding influence of the bodily 
motion of the air around the cannon, it was pointed at right 
angles to its first position, when it was found that the maximum 
velocity came nearer to the cannon. Had the cannon been turned 
in the direction of the line of membranes the retardation would 
probably have become an acceleration. The experiment was, 
owever, of course impracticable. That this apparent retarda- 
tion was not due to the difference in time of action of the mem- 
branes, due to a variation of the force of the wave, is evident 
both from the very slight force required in either case and from 
the fact that the variation noticed is in the wrong direction. 
The charge of powder was considerably varied and the 
heaviest charges, of course, caused the greatest deviation from 
the ordinary velocity. : 
he successive series of experiments, owing to differences in 
the charge and in the loading, gave different values of the 
velocity at any one place, but the facts above stated always 
remained the same. ; : 
Accordingly each series represents the condition of things 
better than the mean of several, and I have here given a table 
of three of the best series. 
The first column represents the distance from the mouth of 
the cannon; the second the values of the corresponding veloci- 
ties in the rear of the cannon, when the charge was one and a 
half pounds; the third when the charge was reduced to half a 
pound, and the last when the cannon was pointed at right 
angles to the line of membranes. 
Velocities reduced to 0° C. 
Rear of 
of cannon. Side of cannon. 
Interval. 14 lbs. Ib. 
10— 30 feet. 1076 feet. teas Hine 
30— 50 1187 1032 1067 
50— 70 1240 1091 1162 
70- 90 1267 1120 1201 
90-110 1262 1114 1188 
0 low intensity must be used for a correct determination of the 
velocity of sound. 
