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IV.— YELOCITT AND ENERGY 0E SMALL SHOT. By JOHN 



RIGBY, M.A. 



[Eeacl, February 19, 1883.] 



The Velocity of projectiles, and .the laws which govern the re- 

 sistance of the air, have been investigated by various methods. 

 Robins, in 1742 ; and Hutton, in 1790, with the aid of the baUistie 

 pendulum, made considerable progress in determining them in the 

 case of spherical balls of moderate size. Between 1839 and 1848 

 experiments with larger spherical shot were made at Metz, by 

 Piobert, Morin, and Didion. The introduction of electrical appa- 

 ratus for measuring short periods of time gave a fresh impulse to 

 these researches, and since 1860 a vast amount of work has been 

 done by British artillerists in this direction. The development 

 of rifled ordnance and elongated shot enlarged the scope of the 

 inquiry. In 1865 the Rev. Francis Bashforth, then Professor of 

 Mathematics to the Advanced Class of Artillery Officers, constructed 

 a chronograph, which bears his name, and gave satisfactory records 

 of the successive periods occupied by rifled projectiles in passing 

 the intervals between ten screens, placed at distances from each other 

 of 150 feet.^ With rare industry Mr. Bashforth has reduced and 

 tabulated the results of experiments extending over sixteen years, 

 and his Tables of Coefficients render it possible to calculate the 

 trajectories, remaining velocities, and times of flight of projectiles 

 of most of the various forms and dimensions likely to occur .in 

 •practice. The Tables for computing the remaining velocities, &c., 

 of Ogival-headed shot embrace all initial velocities from 100 to 

 2900 feet per second." Those for spherical shot range from 500 

 to 1900 feet per second. 



It is unfortunate that no law can be found to express the resist- 

 ance of the air to a projectile in terms of the velocity. For Ogival- 

 headed elongated shot it is stated by Bashforth to vary roughly 



1 'Vide A Mathematical Treatise on the Motion of Projectiles. By Francis Bash- 

 forth, B.D., &c. Asher & Lee, 1873. 



- Vide Fma\ Report of Experiments with the Bashforth Chronograph, W. Clowes 

 ^ Son, 1880, 



