368 
VELOCITY AND PEESSUEE INSTEtiMENTS. 
These results indicate a remarkable concordance between all the instru¬ 
ments, and lead to the conclusion that they are all perfectly trustworthy 
within practical limits, and that no decided preference (as regards relia¬ 
bility) can be given to any one of them. I prefer the Le Boulenge, 
however, for ordinary every-day work, on account of its extreme simplicity 
and facility of manipulation. 
II.—THE CRUSHER-GAUGE. 
The crusher-gauge is employed, as before stated, for registering the 
maximum pressure of the powder gas at the particular point in the bore 
where the apparatus is placed. It superseded the Rodman “pressure- 
gauge ” employed by the Committee on Explosives in their earlier experi¬ 
ments, on account of the extreme variability of the results given by that 
instrument. 
PLATE IV. 
The Crusher Gauge. 
Pig. 1. Pig. 2. 
