220 MAGNUS ON THE DEVIATION OF PROJECTILES, 



surface of the ring — 0*25 inch only in breadth— was but very 

 small, indeed almost vanished, in comparison to the force with 

 which the cylinder, by its rotation, was moved sidewards. 



If we take into consideration the great velocity of the peri- 

 phery of a rotating projectile in comparison to that of the 

 cylinder, it cannot be doubted that the difference of the atmo- 

 spheric pressures against the opposite sides of such a projectile 

 is sufficient to cause the observed lateral deviation. 



II. On the Deviation of Elongated Projectiles, 



The artillery of different countries have lately made experi- 

 ments with elongated hollow projectiles discharged from rifled 

 cannon. Where such projectiles have been used, they have 

 generally had a cylindrical shape, with conical or ogival point, 

 the other end or base being either a plane, or having a hemi- 

 spherical form. The spiral imparts to them a rotation around 

 their axes, i. e. around the line from the cone's apex to the cen- 

 tre of the base, or at least around a line in the immediate vici- 

 nity of this. At all places where such experiments with rifled 

 cannon have been instituted, and the results pubhshed, a similar 

 lateral deviation of the projectiles has been observed*, that is, 

 a deviation always towards the right of an observer behind the 

 gun, and never to the left. In reference to this constant devi- 

 ation, which is far less than that with spherical projectiles dis- 

 charged from smooth barrelled guns, the question arises— can 

 it be explained in a manner similar to the latter? 



That elongated projectiles always deviate towards the same 

 side, is, without doubt, caused by the rifle of the cannon having 

 always the same direction, that is, so that when an observer 

 behind the gun faces the same, and follows the direction in 

 which a point in the rifle recedes from him, he sees it move in 

 the upper part of the barrel from left to right, in the lower from 

 right to left ; or to define it more concisely, as the hands of a 

 clock. 



This description of rifle I will call right-handed ; the other 

 description, progressing in a contrary direction, left-handed. 



As far as I know, no observations have yet been made as to 



• A similar deviation Las lately been noticed when pointed projectiles were 

 fired from rifles. 



