242 F. A. P. Barnard on the Explosive Force of Gunpowder, 
Dr. Hutton, relying upon the approximate correctness of a 
formula which he had constructed for computing the velocities 
of projectiles fired from a gun, and taking as data the velocities 
actually observed, as ascertained by Robins’ pendulum, con- 
cluded the maximum pressure to be somewhere between 1700 
and 2300, thus substantially agreeing with Gay Lussac. The 
results of Dr. Gregory are not materially different from this, the 
maximum pressure being put by him at 2250. 
In the year 1797, Count Rumford communicated to the Royal 
Society of London the results of an elaborate series of experi- 
ments upon the force of gunpowder, in which the estimates of 
pressure had been deduced among other methods from the ob- 
served effect of small charges of powder in lifting heavy weights. 
He puts the greatest force actually observed at about 55,000 at- 
mospheres; but, as the charges filled but a portion of the cavity 
beneath the weight, he infers that the maximum pressure in a 
space entirely filled with the powder ought to be as high as 
101,000 atmospheres. 
e processes and results of Rumford are criticised by Piobert 
(Traité d’Artillerie, Paris, 1847), who regards them as unsatisfac- 
tory. According to his own determination, the maximum pres- 
sure should be about 7500 atmospheres. 
are not to the poe immediately before us. Mr. Woodbridge 
t 
t : 
cylinder, and the explosion being effected without escape of ga 
—without bursting the cylinder. ats 
Mr. Woodbridge also quotes Gen. Antoni, of the Sardinian 
army, as authority for the statement that fine military powder 
in a cylinder of half an inch diameter and height, with 00 
1400 to 1900 atmospheres. ; : 
