THE QUARTERLY 



JOURNAL OF SCIENCE 



OCTOBER, 1S73. 



I. WHAT DETERMINES MOLECULAR 



MOTION?— 



THE FUNDAMENTAL PROBLEM OF NATURE. 



€AN the whole phenomena of nature be explained in 

 terms of matter, motion, and force ? Yes, say the 

 materialists ; and the number of men of science who 

 agree in this view is not only large, but is increasing daily, 

 whilst a doctrine which would scarcely have been tolerated 

 some years ago is now openly maintained by some of the 

 leaders of scientific opinion. A year ago, Mr. James Croll, 

 of the Geological Survey of Scotland, published some argu- 

 ments which arrange the problem in an entirely new light; 

 and we are indebted to the courtesy of the author for a 

 private copy of his paper, which was first published in the 

 " Philosophical Magazine," and from which we condense 

 the following arguments. 



Hitherto, the chief enquiry has been to ascertain the 

 laws which govern the motions of the molecules of matter, 

 but this is not the grand and fundamental problem. It can 

 be subdivided into — (1.) What produces the change — causes 

 motion ? and (2.) What determines or directs it ? 



The answer to the first question is Force, but the second 

 question — not only the more difficult of the two, but also 

 by far the more important — has been lost sight of or con- 

 fused with the first. Physicists have devoted almost exclu- 

 sive attention to the study of the force which takes the path 

 of light, heat, electricity, &c, and upon what does its exer- 

 tion depend, whilst a vastly more important problem, 

 " What is it that causes the force to act in the particular 

 manner in which it does act?" In other words, " What 

 determines the paths along which it acts ?" The great 

 question is, not what gives existence to the motion, but what 

 determines its direction. 



Arguing in this manner, Mr. Croll is led to the proposition 

 that — The production of motion and the determination of motion 

 are absolutely and essentially different. 



VOL. III. (N.S.) 3 K 



