30 



[March 13, 



of solid timber, it will also keep upright through the air, except in 

 much wind, against the effect of which, however, the disk may pro- 

 bably be preserved by inclining the axis of the gun. 



7thly and lastly. The before-mentioned results show that a disk- 

 gun may in certain respects be viewed as a common gun, and in other 

 respects as a gun for throwing an elongated projectile. The former 

 characteristics, as of circular periphery in line of motion, ensure high 

 initial velocity and small strain on the gun ; and the latter, or virtual 

 elongation, ensures the preservation of such velocity ; for it is seen 

 that the requirement of the tangent to the trajectory, so desirable re- 

 specting the proper axis of rotation of a rifle projectile, does not ob- 

 tain in the disk ; and it is also seen that while the rifle projectile can 

 strike effectively but in the prolongation of one of its axes, and that 

 becomes impracticable as elevation increases, the disk has no such 

 limitation, and is not dependent on any one angle of elevation for 

 preserving inviolate the conditions for which elongation is given to 

 any projectile*. 



* On March 20, in the week following that in which the above was read 

 at the Royal Society, four disks were fired at Shoeburyness, in the presence of 

 Col. Taylor, R.A., Commandant and Superintendent, and other officers. The 

 weather was so wet, the tide also not admitting of the gun being loaded early in 

 the day, that four disks only were fired at a target, first of oak, 9 inches thick, 

 and afterwards with about 4 inches of deal behind it ; gun twenty-five yards 

 from target. 



Experiment of March 20, 1862. 



