178 ELEMENTARY PRINCIPLES OF GUNNERY. 



be similar to a smooth bore, but it really is merely a two- 

 grooved rifle with the edges of the grooves rounded off. 

 It is unnecessary, however, here to go into the details of 

 these different methods of grooving, which will be found 

 fully described in the Fifth Book. 



CHAPTER II. 



ON THE ACTION OF GUNPOWDER AND OTHER 

 EXPLOSIVE COMPOUNDS. 



GENERAL REMARKS ACTION OP THE POWDER ON THE PROJECTILE 



MODE OP DETERMINING ITS VELOCITY EPROUVETTES RESISTANCE 



TO THE MOTION OP PROJECTILES THROUGH THE AIR RECOIL 



COMPOSITION OP GUNPOWDER AND GUN-COTTON, AND THE MATERIALS 

 USED FOR FIRING THEM BY PERCUSSION. 



ALTHOUGH much has been done within the last few years in 

 improving the machinery by which bodies are projected 

 through the air, yet little has been discovered since the days 

 of Robins and Hutton, in reference to the principles upon 

 which they act. Indeed many so-called novelties of 1858 

 and 59 are merely old inventions warmed up, and this is more 

 especially the case with regard to Mr. Lancaster's oval bore, 

 which was described in the clearest language in the year 

 1808, as will be fully shown in the proper place. The fol- 

 lowing propositions are chiefly taken from the pages of the 

 celebrated Robins, who is still accepted as the highest 

 authority on the subject. 



Gunpowder when exploded produces a permanently Mastic 

 Fluid. If, says Robins, a red-hot iron be included in a 

 receiver, and the receiver be exhausted, and gunpowder 

 be then let fall on the iron, the powder will take fire, and 

 the mercurial gauge will suddenly descend upon the ex- 

 plosion; and though it immediately ascends again, yet it 

 will never rise to the height it stood at before, but will 

 continue depressed in proportion to the quantity of powder 

 which was let fall. The same fact may be shown when gun- 



