1868.] Mr. Bashforth on the Resistance of the Air to Projectiles. 261 



le pouvoir electro-moteur des muscles et des actes chimiques de la respira- 

 tion musculaire. Cette relation est mise hors de doute par des experiences 

 rigoureuses et tres- varices. 



J'espere pouvoir plus tard communiquer a la S. R. la suite de ces 

 trauaux. 



II. "Oq the Resistance of the Air to the Motion of Elongated 

 Projectiles having variously formed Heads.^' By the Rev. F. Bash- 

 forth^ B.D., Professor of Applied Mathematics to the Advanced 

 Class of Artillery Officers, Woolwich. Communicated by Pro- 

 fessor Stokes, Sec. R.S. Received January 30, 1868. 

 (Abstract.) 



These experiments were undertaken with a view to determine the resist- 

 ance of the air to some forms of heads of elongated shot which were likely 

 to be of practical use. The chronograph used was the one described in the 

 Proceedings of the Royal Artillery Institution for August 1866*, which 

 was constructed on the plan of the Greenwich instrument. Ten screens 

 were placed in a line at intervals of 150 feet, the first being 75 feet from 

 the gun. The following were the forms of the heads, and ten shot of each 

 kind were prepared : — 



(1) Hemispherical , solid. 



(2) Hemispheroidal (axes as 1 : 2) solid. 



(3) Ogival (struck with a radius = 1 diameter) . . solid. 



(4) Ogival (struck with a radius = 2 diameters) . . solid. 



(5) Ogival (1 diameter) hollow. 



(6) Ogival (2 diameters) hollow. 



(3) and (5) as well as (4) and (6) had respectively the same external 

 forms, but the solid were nearly double the weight of the hollow shot. The 

 gun used was a 40-pounder M.L., and the diameter of the shot was 4*7 

 inches. 



It was found, as in the trial experiments of 1865, that, if s be the space 

 described in time t after passing the first screen, then, approximately, 



from which it follows that, if v be the velocity at time 



1 



v= -, 



a-\-2bs 



and the retarding force 



.^-25i;\ 



If V denote the velocity when s=0, then 



Published separately by Bell and Baldy, 1866. 



