NATURE OK THINGS. 449 



this fact is no other than the same we are now handling. For 

 the concussion of the body occasions an excessive impetus 

 in all its parts and particles, to effect in some way or other 

 their extrication and freedom. The body, therefore, not 

 only acts and flies forth in a straight line, but strives to move 

 from every point in it at once, and, therefore, whirls round ; 

 for in both ways it somewhat relieves itself of its impulse. 

 Now this, which in the harder solids is a somewhat recon 

 dite and latent property, is in the softer ones evident, and 

 so to speak palpable. For as wax, and lead, and similar 

 soft bodies, when struck with a mallet, give way not only 

 in the line of percussion, but laterally every way ; so in like 

 manner, hard or resisting bodies move in a straight line 

 and periphery at once. For the retrocession of soft bodies 

 in their substance, and of hard ones in their place, is the 

 same in its principle, as is evidently seen in the structure of 

 the soft body, and in the affection of the hard one, exhibited 

 in its flight and volant path. Meantime let none think 

 that besides this motion (which is the cardinal point), I 

 do not ascribe a certain degree of effect to the conveyance 

 of the air, which is capable of assisting, obstructing, modi 

 fying, and regulating the principal motion ; for its power 

 is far from being inconsiderable. And this doctrine of 

 violent or mechanical motion (which has been hitherto un 

 known), is, as it were, the fountain-head of practical me 

 chanics. 



Of the cause of Motion in Fire-arms, which has been hitherto 

 investigated only in part, and that part comparatively un 

 important. 



IX. 



The theory of fire-arms, of a motion so powerful and so 

 remarkable, is imperfect, and in the more important part, 

 defective. For it is said in explanation that the gunpowder, 

 after having been converted into flame and volatilized, ex 

 pands and occupies more space ; whence it follows, that 

 as two bodies cannot exist in the same space, otherwise a 

 jumbling of their dimensions would ensue, or the elementary 

 form be destroyed, or a preternatural arrangement of the 

 internal parts of the body be the effect (for this is what 

 they say), that the impeding body is ejected or broken. 

 And what they say contains something. For this tendency 

 is both an affection of matter, and an ingredient in the 

 motion itself. Yet they err in this, that in their over hasty 



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