MECHANICAL BASIS OF NATURAL SCIENCE, 257 



Mach says similarly, 



" I hope that the science of the future will discard the idea of cause 

 and effect, as being formally obscure ; and in my feeling that these ideas 

 contain a strong tincture of fetishism, I am certainly not alone."* 



Professor Hicks calls matter, time, and space the data of a 

 mechanical theory. But on this view matter has become a mere 

 centre of force ; and even the word " force " is discarded in favour 

 of the mere calculation of rapidity of movement or amount of 

 acceleration. And in the same way it is recognised that space 

 and time are purely relative expressions with no absolute value. 



Lord Kelvin said once that he could never satisfy himself 

 until he could make (mentally, I presume) a mechanical model 

 of a thing. As long as he could not make a mechanical model 

 all the way through, understanding was impossible. From 

 the point of view of the Descriptive School this statement is open 

 to doubt. We might have a mechanical model which would 

 repeat with mathematical accuracy all the ultra-microscopic 

 processes of the minutest molecules that take part in a chemical 

 combination. Yet nothing would thereby be, in a true sense of 

 the word, explained. We should have a picture of the phenomena, 

 but we should be as far as ever from understanding the inner 

 forces by which these changes are brought about. In fact our 

 problem would be doubled, for we should want the model itself 

 to be explained as well as the section of reality which it was 

 supposed to represent. 



2. In the second place, there is a theory mentioned in the passage 

 referred to above from Professor Hicks that the phenomena 

 of light, of electricity, of magnetism, and of other forms of radiation, 

 cannot be mechanically explained, or even described, without 

 the hypothesis of an ethereal medium. Thus in order that the 

 mechanical theory may be complete it must be assumed that 

 " all phenomena are manifestations of one continuous medium." 



In the same way matter itself, one of the data (according to 

 Professor Hicks) of the mechanical theory, is frequently explained 

 or described as a mode or modification of the ether. 



" According to Kelvin the ether is the locus of those points at which 

 the ether is animated by vortex motions. According to Reimann it 



is the locus of those points at which the ether is being destroyed. According 

 to Larmor it is the locus of those points at which the ether is undergoing 

 a kind of torsion." 



Now this ether, which enters so largely into the scientific 

 description of Nature, is not in itself mechanical, and cannot 

 be described in mechanical terms. It is commonly said to be 

 inert, incompressible, frictionless, inviscid, structureless, — all 

 negative terms. As Clifford says, 



" The liquid of Sir William Thomson's hypothesis is continuous, infinitely 

 divisible, not made of molecules at all, and it is absolutely frictionless. 

 (In these ways it is sharply contrasted with all the liquids with which 

 we can experimentally deal). It is a mathematical fiction." 



* " Popular Scientific Lectures," English Translation, p. 253. 

 f (This summary is taken from " The New Physics," by Prof. Poincare, 

 p. 167). 



