ISth February, 1917. 



THE FLIGHT OF A BULLET. 

 By Professor W. B. Morton, M.A. 



(Abstract.) 



The subject of the lecture is the motion of a modern elongated 

 bullet discharged from a rifled barrel, with special reference to 

 the British service rifle and ammunition. The advantage of 

 imparting a spin to the bullet was recognized as early as the 

 16th century. A round bullet leaving a smooth-bore fire-arm 

 acquires an accidental spin which varies from one discharge to 

 another and causes erratic shooting. By imi)arting a definite 

 rotation round the direction of motion the flight becomes much 

 more regular. It is probable that the idea was suggested by 

 experience acquired in throwing a javelin or dart. Practical 

 difficulties prevented the adoption of the rifled barrel until quite 

 recent times. The bullet had to be a tight fit for the barrel and 

 so required a great force to ram it down from the muzzle. Breech- 

 loading, as an obvious way out of this difficulty, was thought of 

 at an early stage, but this did not become practicable until a way 

 could be found for preventing the leakage of flame backwards 

 through the breech. Col. Boxer's invention of the brass cartridge- 

 case provided this, and following upon it, a little before 1870, 

 came the universal adoption of the rifle as a military weapon. 

 The principle of the spinning bullet becomes of fundamental 

 importance with the introduction of elongated projectiles, for, as 

 will be seen, these will not fly point forward unless they are 

 spun. 



The motion of the bullet may be considered in three stages, 

 (1) in the barrel, (2) in the air, (3) after impact on the body 

 struck. 



