356 



THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



surely to be to endeavor to think out the simplest 

 method of arriving at a result, keeping in view 

 the fact that simplicity is necessary to the orderly 

 working of mechanical processes, and that the 

 real point to admire is a simple method of attain- 

 in ' a mechanical result, because it is unique, not 

 a complicated method (which may be conceived 

 to be indefinitely varied). The beautiful kinetic 

 theory of gases affords the simplest method to 

 the solution of the problem of the constitution 

 of the physical media in space, and in the case 

 of the gravific medium it may be proved to be 

 the only solution which can harmonize with ob- 

 served facts. 1 



When we realize the practically unlimited in- 

 tensity of the concealed energy that may thus ex- 

 ist in space (in the simple form of finely-subdi- 

 vided matter possessing a high velocity) one may 

 cease to wonder at the sudden energy transferred 

 to a mass of gunpowder (or a shell) in the act of 

 explosion, and realize how this otherwise incom- 

 prehensible and extraordinary effect can take 

 place. It would be illogical to consider a fact 

 extraordinary, or that a rational explanation for 

 it is less urgent, because it is commonplace, and 

 precisely because there is this tendency it ought 

 to be specially guarded against. In the case of 

 the explosion we have in principle simply the 

 transference of motion from minute particles of 

 matter (where the motion is therefore invisible) 

 to grosser matter, in the form of clouds of vapor 

 and palpable fragments of matter (when the mo- 

 tion is visible) ; and therefore to the superficial 

 bodily eye there naturally appears to be an actual 

 creation of motion. If the motion (before trans- 

 ference) were not invisible, it would not be me- 

 chanically efficient for the object to be attained ; 



1 It may be observed that in the case of any me- 

 dium constituted according to the kinetic theory, the 

 velocity of the particles of the medium is equal to the 

 velocity of propagation of a wave in the medium — 



V5 



See result appended by Prof. Maxwell to paper " On the 

 Mode of Propagation of Sound" {Philosophical Maga- 

 zine, June, 1877). 



for unless the moving particles of matter consti- 

 tuting the medium were small, it would be im- 

 possible to concentrate a considerable intensity 

 of energy within a small volume of space. In the 

 case of any powerful or intense motive source, 

 velocity of the particles must evidently be relied 

 on rather than mass (since mass occupies space, 

 and prevents concentration of the energy). There 

 could be no logical ground why problems of this 

 nature should be regarded in any other light than 

 as ordinary engineering or mechanical problems, 

 to be explained by the light of reason and com- 

 mon-sense. There would appear to be a kind of 

 prejudice in regard to thinking on these subjects 

 which requires to be surmounted or dissipated by 

 logic. It may seem bold to say it, but scientific 

 reform is called for in this respect. Ability is by 

 itself of no avail without attention. Reform, in 

 the sense of a more general attention being di- 

 rected to subjects whose real interest would dis- 

 close itself on examination, is what is required. 



In regard to the subject of recurring changes 

 in the universe, this opinion appears to have been 

 held by Sir W. Grove (" Correlation of Physical 

 Forces," p. 67), though he does not go into any 

 explanation as to the particular conditions re- 

 quired to bring about the result. He remarks 

 relative to this subject (p. 67) : " Enlarged ob- 

 servation may prove that phenomena seeming to 

 tend in one direction will turn out to be recur- 

 rent, though never absolutely identical in their 

 recurrence ; that there is throughout the uni- 



verse gradual change, but no finality ; 



that 



no star or planet could at any time be said to be 

 created or destroyed, or to be in a state of abso- 

 lute stability, but that some may be increasing, 

 others dwindling away, and so throughout the 

 universe, in the past as in the future." 



Humboldt also says, as regards this point 

 (Preface to "Cosmos"), "I would therefore 

 venture to hope that an attempt to delineate 

 Nature in all its vivid animation and exalted 

 grandeur, and to trace the stable amid the vacil- 

 lating, ever-recurring alternation of physical 

 metamorphoses, will not be wholly disregarded 

 at a future age." — Quarterly Journal of Science. 



