of Projectiles thrown from Cannon. 227 



lonel Grobert, we shall now add a short account of the me- 

 thods hitherto employed in researches of the same kind. 



It is only about sixty years ago that mathematicians be- 

 gan to apply to the theory of projectiles. Benjamin Robins 

 appears to us to have opened the way, or at least to have 



f)ublished the first experiments worthy the attention of phi- 

 osophers, and to have employed, for determining the initial 

 velocity of musket bullets, a pendulum, against which he 

 threw his projectiles, and the sought-for velocity was de- 

 duced from the amplitude of the oscillation : the same ma- 

 thematician, when about to make particular experiments on 

 gunpowder, deduced his results from the recoil of a small 

 cannon attached to the lower part of the same pendulum *. 



The chevalier d'Arcy, of the Academy of Sciences, about 

 eight or ten yevs after Robins's work appeared, published, 

 in the Memoirs of the Academy for 1731, a paper on the 

 theory of artillery, containing a series of experiments made 

 with great skill and care, and for which he employed, nearly 

 in the same circumstances, two pendulums ; agamst one of 

 these he fired the ball, while the other, from which the 

 small cannon was suspended, served to measure the recoil. 

 In this manner he made those important experiments re- 

 lated in Essais d'ane Thcorie de I Ar tiller le, published by 

 the same author in 176O. 



Fifteen years after, Dr. Button, of the Royal Academy, 

 Woolwich, made new experiments with the pendulum and 

 projectiles, much heavier than those employed by Robins^. 

 An account of them n)ay be seen in the Philosophical 

 Transactions for 1778. 



About the same year count Rumford resumed and im- 

 proved the method of making such experiments by means 

 of a pendulum. Rediscovered a very simple way of sus- 

 pending the cannon, in such a manner that the recoil took 

 place without the axis ceasing to be horizontal. Dr. Hutton 

 bestows great praise on these experiments, which are de- 

 tailed in the Philosophical Transactions for 1781, and which 

 have since been printed with considerable additions in a coir 

 lection entitled Philosophical Papers, &c. London 1802. 



In the last place. Dr. Hutton was employed during the 

 years 1763, 1784, 1765, and 1786, on a numerous series 

 of experiments, made with great care and expense, in regard 

 to both kinds of pendulum. The collection of his memoirs, 

 inserted in the Philosophical Transactions, and lately trans- 



• See his Principle* of Gunnery. 



P 2 latcd 



