26 Experiments iipon Gunpowder. 



who wish to see more on the subject to Mr. Robins's 

 New Principles of Gunnery ; to Professor Euler's Ob- 

 servations upon Mr. Robins's Book ; and lastly, to 

 Dr. Hutton's Paper on the initial Velocities of Cannon 

 Balls, published in the Transactions of the Royal So- 

 ciety, for the year 1778. 



If a denote the length from the axis of the pendulum 

 to the ribbon which measures the chord of the arc of its 

 vibration ; 



g the distance of the center of gravity below the axis 

 of the pendulum ; 



f the distance of the center of oscillation ; and 



// the distance of the point struck by the bullet from 

 that axis ; 



c the chord of the ascending arc of the pendulum ; 



P the weight of the pendulum ; 



b the weight of the bullet, and 



v the original velocity of the bullet ; 



z, = i x 5+ix-4> 



a bh / ^2/1 



is a theorem for finding the velocity upon Mr. Robins's 

 principles. 



bh 2/ 



is the theorem proposed by Professor Euler, who has 

 corrected a small error in Mr. Robins's method ; and 



v = 5-672 



* Put the rational part -- X -^ -f- -^ + A -= n and express / in thou- 

 a b /t 2f 



sandth parts of a Rhynland foot ; then the velocity with which the ball 



strikes the pendulum will be = - /I Rhynland feet in a second. 



4 y 2 



