268 Mr. A. Mallock. Air Resistance encountered by [Nov. 3, 



tion of equal parts of black lead and tallow. These bullets answered 

 admirably, and in July of the year I completed a series of experiments 

 going up to velocities of 4500 f.s. 



456 



FIG. 1.- 



- Aluminium shot used in air- resistance experiments, 

 actual size. Weight 23'3 grains. 



Scale five times 



The results of these experiments are given in the figs. 2 and 3, 

 together with the results obtained from the shooting by Major 

 Fremantle and Colonel Mellish, with the service bullet, and also, for 

 comparison, Professor Bashforth's results. 



Curve A, fig. 2, gives the velocities in feet per second, found at 

 -various ranges, and curve B, the loss of velocity in a distance of 

 5 yards. (It may be noted that at 4500 f.s. the retardation experi- 

 enced by the light shot used was 205000 feet per second per second.) 

 Curve A, fig. 3, gives the deduced resistance (in Ibs. per square inch), 

 encountered by the projectile, in terms of velocity. 



To determine the resistance of an ogival-headed shot from the 

 resistance experienced by a flat-headed shot moving with the same 

 velocity, the resistance of the latter must be multiplied by a co-efficient, 

 which is generally taken as J. 



If the circular edges of the flat head are slightly rounded this value 

 is nearly correct, but I have found by experiment that when the edges 

 of the flat are quite sharp (as they were with the aluminium cylinders 

 used), the co-efficient is rather less than half.* 



In curve B, fig. 3, the co-efficient was taken as 2 \, and this curve 

 represents, at any rate, very approximately, the resistance experienced by 

 -an ogival-headed shot. Curves C and D, fig. 3, give respectively, the 

 results obtained from the experiments of Major Fremantle and Colonel 

 Mellish, made with the '303 rifle, and by Professor Bashforth from his 

 experiments with large guns. 



* I hope to determine the true value more accurately than I have hitherto had 

 time to do. Probably it is not a constant for all velocities, but approximates to a 

 constant as the velocity increases. 



