Experiments iipon Gunpowder. 69 



marked upon the ribbon, by black lines drawn across it, 

 and the word proof may be written upon the middle line; 

 or if the recoil be uniform (which it will be, to a suffi- 

 cient degree of accuracy, if care is taken to make the 

 experiments under the same circumstances), then the 

 proof mark is to be made in that part of the ribbon to 

 which it was constantly drawn out by the recoil in the 

 different trials. 



The recoil with a known charge of standard powder 

 being thus ascertained, and marked upon the ribbon, 

 let an equal quantity of any other powder (that is to be 

 proved) be fired in the same barrel, with a bullet of the 

 same weight, and every other circumstance alike, and if 

 the ribbon is drawn out as far or farther than the proof 

 mark, the powder is as good or better than the stand- 

 ard ; but if it falls short of that distance, it is worse 

 than the standard, and is to be rejected. 



For the greater the velocity is with which the bullet 

 is impelled, the greater will be the recoil ; and when the 

 recoil is the same, the velocities of the bullets are equal, 

 and the powder is of the same degree of strength if the 

 quantity of the charge is the same. And if care is 

 taken in proportioning the charge to the weight of the 

 bullet, to come as near as possible to the medium pro- 

 portion that obtains in practice, the determination of the 

 goodness of gunpowder from the result of this experi- 

 ment cannot fail to hold good in actual service. 



Fig. 14 represents the proposed apparatus drawn to a 

 scale of one foot to the inch. <2, b, is the barrel sus- 

 pended by the pendulous rods c } d ; and r is the ribbon 

 for measuring the recoil. 



The length of the bore is 30 inches, and its diameter 

 is one inch, consequently it is just 30 calibres in length, 

 and will carry a leaden bullet of about 3 ounces. 



