VELOCITY AND PRESSURE INSTRUMENTS, 
865 
[Continued?) 
Nature oi 
powder 
and charge 
Velocity 
by 
Navez- 
. Leurs 
at 105 ft. 
Velocity 
by Le 
Boulenge 
at 105 ft. 
J Difference. 
Nature of 
powder 
and charge. 
Velocity 
by 
Navez- 
Leurs 
at 105 ft. 
Velocity 
by Le 
Boulenge 
at 105 ft. 
Difference. 
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On reference to the column headed u Difference/’ it will be seen that the 
difference between the velocity of any particular round, as indicated by either 
of the instruments, is very trifling, the variations, in the velocity of succes¬ 
sive shots being due to the fact that various lots and descriptions of powder 
were being tested at the same time, and, so far from interfering with the trial 
of the two instruments, it serves rather to demonstrate more clearly the 
wonderful agreement in their indications. 
For the purpose, however, of more accurately determining the relative 
value of the two chronographs, the velocity of 50 rounds of various lots of 
Waltham Abbey B.L.G., and 50 rounds of Waltham Abbey R.F.G. powder, 
have been taken from the table, and the mean velocity and the mean differ^ 
ence of velocity calculated for each instrument, as follows:— 
