444 Professor Tyndall [May 3, 10, and 17, 



The flat stone is thus inscribed : — 



En Baviere 



Lieutenant-General 



Chef de I'Etat-Majnr General, 



Conseiller d'Etat, 



Ministre de la Guerre, 



En France 



Membre de I'liistitut, 



Acade'mie des Sciences. 



Rumford'8 Scientific Work. 



As a factor in human affairs, Rumford ascribed to gunpowder a 

 dominant position. No other invention had exercised so great an 

 influence. Hence the arduous labour he expended in determining its 

 action. At StoneLT,nd Lodge, the country seat of Lord George 

 Germain, in the year 1778, his inquiries into the force and applica- 

 tions of gunpowder began. He directed his attention to the position 

 of the vent, the weight and pressure of the charge, its bursting jjower, 

 the quickness of combustion, the weight and velocity of the projectile, 

 the effect of windage, and to many other matters of interest to the 

 gunner. On all these questions he threw important light. The 

 velocity was determined in two ways : first, by the ballistic pendulum, 

 invented by his predecessor and namesake Benjamin Robins ; and 

 secondly from the recoil of the gun itself. The ballistic pendulum is 

 a heavy mass, so suspended as to be capable of free oscillation. 

 Against it the bullet is projected, and from the weight of the bullet, 

 the weight of tlie pendulum, and the arc, or distance, through which 

 it is urged by the bullet, the velocity of the latter may be calculated. 



To determine the recoil of the gun, he had it suspended by a 

 bifilar arrangement, which permitted it to swing back when it was 

 fired. Action and reaction being equal, the momentum of the gun 

 was the momentum of the bullet on leaving the gun, and from the 

 weight of the piece, and the arc of recoil, the velocity of the bullet 

 was computed. The agreement between the results obtained by these 

 two methods was in many cases remarkable. Until quite recently, 

 Rumford's experiments on the force of gunpowder were considered to 

 be the best extant. A mind so observant could not fail to notice the 

 heating effects produced by the percussion of the bullet against its 

 target, and by the jar of the gun at the moment of its discharge. By 

 such facts he was naturally led to reflect on that connection between 

 mechanical power and the generation of heat which he afterwards did 

 so much to illustrate and develope. 



The phenomena both of light and heat fascinated liim ; and we 

 accordingly find him from time to time abandoning practical aims, 

 and seeking for knowledge which had no apparent practical outcome. 

 Thus we see him experimenting on the action of green vegetables and 



