310 Mr. S. T. Preston on the Kinetic Theory of Gravitation. 



motion simply consist in small particles of matter in a state of 

 rapid motion ; or there is nothing occult about the subject at 

 all, as indeed obviously principles of reasoning are independent 

 of size. The minute size (and consequent invisibility) of the 

 particles is necessary to the efficiency of the media as powerful 

 motive agents, since minuteness of size is necessary to render 

 a high velocity possible for the particles, without producing 

 disturbing effects among the matter immersed in these media. 

 There is one very noteworthy point that cannot be too dis- 

 tinctly kept in view in connexion with this subject. It is the 

 fact that the high intensity of the stores of motion possessed 

 by these media, and which renders them so important, serves 

 to conceal their existence from the senses. Thus the higher 

 the intensity of the store of motion enclosed by these media, 

 and consequently the greater their capacity for practical 

 utility, the more likely (if the mere evidence of the senses 

 were relied on) is their existence to be forgotten. For it may 

 be proved beforehand, by the kinetic theory of gases, that the 

 greater the velocity of the component particles of a medium, 

 and consequently the greater the value of the store of energy 

 enclosed (which may even reach an explosive intensity), the 

 more does the presence of the medium elude detection, because 

 the resistance opposed by the medium to the passage of bodies 

 through it diminishes as the velocity of the particles increases. 

 The less indication the mere senses (unaided by reason) afford 

 of the existence of such media, the higher, therefore, should 

 we be warranted in inferring their importance to be. Even 

 independently of all question of the existence of these media, 

 it may be proved beforehand that, if media did exist and en- 

 close stores of motion to an enormous intensity, they icould be 

 concealed. This is, no doubt, a remarkable fact, and contrary 

 to preconceived ideas, as it would doubtless appear on the first 

 thought that the higher the intensity of a store of energy ex- 

 isting in space, the more likely would it be to make itself 

 apparent to the senses, whereas precisely the contrary is found 

 to be the fact. This forms a notable instance of one of those 

 cases where analysis completely reverses preconceived ideas. 

 It is possibly the absence of appreciation of this fact that may 

 in some way account for the failure of the most striking proofs 

 of nature to carry their practical teaching, as for example, 

 the sudden setting free of concealed motion in the explosion 

 of a mass of gunpowder. Here to the mere bodily senses, we 

 have apparently an actual creation of motion. Something 



power derived («'. e. that the work done should be the equivalent of the 

 machinery expended), it is at least so far certain that no remedy for this 

 could be discovered unless the physical conditions of the case were re- 

 cognized. 



