a Nexo Dynamico-Chemical Principle. 173 



quaintance with natui'e is requisite. The constituent principle 

 of the attractive and repulsive powers, and their mode of ope- 

 ration, may differ from all we can deduce in comparison. 

 When we therefore perceive matter, once in a state of motion, 

 gradually arrive at a state of rest, without any visible trans- 

 ference of its power, having no direct proof to the contrary, 

 we are induced to consider it absolutely lost. Still the fol- 

 lowing simple analogy appears to afford evidence of the con- 

 trary, and authorizes the conclusion, that momentum like 

 matter cannot by natural means be annihilated, the existence 

 of both being of equal importance in the oeconomy of nature, 

 A body when falling towards the earth, gradually accumulates 

 a quantity of momentum, which is visibly lost when it arrives 

 at the ground. In this instance the momentum, before it is 

 transferred to the falling body, is invisible; why may not, there- 

 fore, the same momentum after collision, be again reduced to 

 the same invisible state without being actually destroyed? 

 The manner in which it appears and disappears is certainly 

 different, but the latter may be governed by laws as unalter- 

 ably fixed as those of the former, although from the com- 

 plexity of the attending circumstances their influence cannot 

 so readily be appreciated. Thus after collision, in the above 

 example, undulations or vibratory motions are always ob- 

 served to take place. These changes are influenced by the 

 nature of the composing substance, which again is an imme- 

 diate consequence of the peculiar molecular forces of the ulti- 

 mate constituent particles. Since we have this reason to sup- 

 pose that their molecular forces are, like gravitation, subject 

 to fixed laws, and are every way of like importance and uni- 

 versality, it becomes highly probable that they are alone the 

 invisible agents which abstract this momentum of collision, 

 without any evidence of its existence being afterwards per- 

 ceived. 



These views of the transference of motion are further de- 

 serving of attention by their accordance with the simplicity 

 of nature, and by tending to clear science of all those auxi- 

 liary causes, the introduction of which, though necessary to 

 explain the contrary hypothesis, has yet proved a serious 

 obstacle to the progress of true philosophy. If founded on 

 truth, they induce a lively hope that matter and motion alone 

 will be found suflicient to explain all the pha'uomena attend- 

 ing the grand cycle of nature's operations, and that that 

 system of unity and simplicity which the advancement of dis- 

 covery is always bringing further into view, will at length be 

 completely unfolded, and all the physical sciences eventually 

 traced to the varied development of these two principles. 



Two 



