130 ANNUAL OF SCIENTIFIC DISCOVEEY. 



the body a steady motion. Various plans have been from time to 

 time tried, with the object of imparting to long projectiles a steady 

 flight. They have been made with spiral grooves cut externally on 

 their periphery, or internally from front to rear, in the expectation 

 that the resisting action of the atmosphere acting on the inclined sur- 

 faces would give the requisite spinning motion. Again, they have 

 been made very long, and furnished with fins or feathers, in order 

 that they may be propelled on the principle of the arrow, but no 

 practically successful results have as yet brought projectiles of this 

 kind into use. The required object is, as is well known, readily and 

 successfully effected by propelling the elongated projectile from a 

 rifled barrel, that is, a tube having its interior made of such a spiral 

 form that the projectile, while it is propelled from the breech to the 

 muzzle, is turned round its axis of progression : a rotary motion is 

 thus imparted, which is retained by the advancing projectile, and 

 gives it the required steady motion. The elongated bullet was first 

 used with rifled small-arms, either polygrooved or fluted, or, like the 

 Enfield, having three grooves. The length, however, was limited; 

 and various attempts were made to fire longer projectiles, compounded 

 of various metals, and of various shapes, so that by changing the posi- 

 tion of the centre of gravity they might be propelled point foremost. 

 But if made beyond a certain length they were always found to turn 

 over at moderately long ranges. Mr. Whitworth was the first to 

 enunciate the principle that projectiles of any requisite length could 

 be successfully fixed by giving them rapid velocity of rotation, wnich 

 should be increased in proportion with their increased length. He, as 

 is well known, uses rifles having a spiral polygonal bore, in which all 

 the interior surfaces are made effective as rifling surfaces. The suc- 

 cess of the elongated projectile having been established in the case of 

 small-arms, their employment with ordnance followed as a natural 

 consequence. Rifled ordnance were, therefore, called into existence 

 to meet the requirements of the time. In fact, rifled cannon may be 

 considered as a rifled musket made with enlarged proportions. 



The importance of giving to ships intended for high speed the shape 

 best suited to facilitate their progress through water is now universally 

 acknowledged; and Mr. Whitworth considered that it was neces- 

 sary to ascertain, by reasoning upon similar grounds, and by experi- 

 mental research, what was the proper shape to give his projectile, 

 so that it might be propelled through the air under conditions most 

 favorable to precision and range. He, after numerous corroborating 

 experiments, decided that the projectile adopted by him was the best. 

 It has a taper front, having nearly the external section of what math- 

 ematicians term the solid o^ least resistance, the curve being somewhat 

 rounded ; the rear is made to taper in such proportion that the air dis- 

 placed by the front is allowed readily to close in behind upon the 

 inclined surfaces of the rear part. The middle part is left parallel to 

 the required distance, to provide rifling surfaces, and obviate windage. 

 The results of long and n-peated trials show that this form of projectile 

 gives much greater precision and a superiority of range, varying from 

 fifteen to twenty-five and thirty per cent, (according to the elevation 

 and consequent length of range), as compared with a projectile of the 

 common rounded front and parallel rear end. At low elevations, 



