NUTHALL AND BOUCHER'S RIFLES. 321 



sided, especially if the grooves are deep, causing a consider- 

 able amount of extra friction, and consequently retardation 

 by its grinding motion, while passing through the air. I 

 have therefore fixed on five, though, from my style of 

 grooving, many have supposed the barrel to be a smooth- 

 bore. 



" In order to understand the mode of grooving thoroughly, 

 I must ask the reader to draw for himself, on as large a 

 scale as he pleases for the sake of distinctness, the geometrical 

 figure called a pentagon. Then, in the centre, let him draw 

 a circle, so that its edges may just touch the sides of the 

 figure. This circle is to represent the end of the bullet. 

 The next process is to round off the angles of the figure to 

 rather less than a third of their original depth, when they 

 will appear to be broad, shallow grooves, somewhat like the 

 second diagram above; the first diagram representing the 

 figure before the angles were rounded off. 



" The twist of the spiral is at the rate of one turn in five 

 feet, which generates a rotary motion quite sufficient for a 

 range of one mile, for, as there is little friction, comparatively 

 speaking, to retard the progress of the bullet in the barrel, 

 it proceeds with greater velocity after leaving the muzzle, 

 thus rendering a less amount of twist necessary than in a 

 barrel having more friction. 



" Taking into consideration all the experiments I have 

 made myself, all I have witnessed in other quarters, and all 

 the experimental reports I have read on the subject, this is 

 the mode of grooving which I still prefer, and which I 

 recommended to our authorities in the autumn of 1853, and 

 again in 1855. I have loaded and fired hundreds of rounds 

 from such a barrel without the slightest trouble, the last 

 bullet going down as easily as the first; in fact, a glance at 

 the diagram will show any man conversant with the subject 

 that there can be no friction that cannot be overcome by 

 merely pressing the ramrod gently and steadily down, so 

 that the shape of the bullet cannot be destroyed, nor the 

 powder caked, by the bullet being jammed down upon it. 



" This mode of grooving requires only attention on the part 

 of the workman, without which any sort of grooving becomes 

 worse than useless, disappointing and deceiving the man who 



Y 



