98 



NATURE 



[JUN] 



1892 



in terms of matter." By what logic or grammar can 

 understand be substituted for are acquainted with or 

 know J and by what right is a description twisted into a 

 definition ? Words in their usual meanings may, how- 

 ever, be of little consequence to a writer who persists in 

 using the English word resume in the French sense. It 

 seems to us that Prof. Pearson has altogether missed 

 the significance of the word "objective" as used by 

 Prof. Tait, to whom, as everyone knows or should know, 

 we owe the first clear presentation of the dogma that force 

 has no objective existence. At any rate, we are surprised 

 to find in the " Grammar of Science " no distinct reference 

 to the two grand principles of all science— to wit, the 

 conservation of matter and the conservation of energy. 

 This omission by an avowed writer on the principles of 

 science is certainly matter of surprise. As regards the 

 views of force expounded in the book, the author is 

 simply a disciple of Prof, Tait. If not, he must 

 regard Tait as " that worst of plagiarists "—the man who 

 made the discovery before he did. Prof. Pearson has, 

 indeed, a certain fatality for having dealings with that 

 most unsatisfactory kind of plagiarism. In Tait's " Pro- 

 perties of Matter," first edition (1885), paragraph 162, are 

 written these words : — 



" Sir W. Thomson has shown that if space be filled 

 with an incompressible flnid, which comes into exist- 

 ence in fresh quantities at the surface of every particle 

 of matter, at a rate proportional to its mass, and is 

 swallowed up at an infinite distance, or, if each particle 

 of matter constantly swallows up an amount proportional 

 to its mass, a constant supply being kept up from an 

 infinite distance, — in either case gravitation would be 

 accounted for." 



If this is not essentially the theory of "ether-squirts" 

 which " the author has ventured to put forward," what 

 then is the ether-squirt? The quotation just given 

 occurs in Tait's seventh chapter, which, being empty of 

 " red rags," probably failed to come within Prof. Pearson's 

 sphere of perception. 



Be it noted that we do not criticize our author's views 

 as to the significance of such words as force and cause ; 

 but we cannot say we fancy his critical tone towards 

 others. He himself uses the phrase " acceleration of A 

 due to B," but warns the reader in a footnote against 

 taking the phrase in its literal sense ; yet anybody else 

 from Newton down the centuries who has dared to use 

 similar phrases is sneered at as a searcher after the 

 unknowable " why." 



For example, in his criticism of Newton's first law 

 of motion, what right has he to say that Newton " was 

 thinking of force in the sense of mediaeval meta- 

 physics as a cause of change in motion " .? What is the 

 perceptual or conceptual basis of this assumed certitude ? 

 Newton was probably thinking of vis impressa, the 

 very grammatical form of which shows that there was 

 nothing ultimate implied in the vis. After discussing the 

 various kinds of vires that have to be dealt with, and 

 pointing out clearly by definitions and descriptions their 

 precise meanings, Newton concludes one paragraph in 

 these words : — 



" Mathematicus duntaxat est hie conceptus : Nam virium 

 causas et sedes physicas jam non expendo." 



NO. I 179, VOL. 46] 



Then a little further on we read : — 



" Has vires non physice sed mathematice tantum con- 

 siderando. Unde caveat lector, ne per hujusmodi voces 

 cogitet me speciem vel tnodum actionis causaynve aut 

 rationem physicam alicubi definire vel centris {quce sunt 

 Puncta mathematica) vires vere et physice tribuere ; si 

 forte aut centra trahere, aut vires ccntrorum esse dixero.,^ 



Can it be that Prof. Pearson has never read Newton's 

 " Principia," and has he forgotten that the complete title 

 is " Philosophiae NaturaHs Principia Mathematica".? To 

 insinuate that Newton's laws of motion (which, it 

 should never be forgot, are intimately associated with 

 the Definitiones) are incomplete because they may not 

 possibly apply to corpuscles other than those of " gross " 

 matter, to corpuscles of all imaginable types in short, 

 implies a complete misapprehension of the whole purpose 

 and scope of the " Principia." Again, our grammarian 

 pounces upon the word " body," or corpus, as used by 

 Newton, who should at least have used particle or cor- 

 puscle. In Definition I. will be found the meaning 

 intended by Newton to be attached to the word corpus; 

 but in any case the whole phraseology of the first law 

 is quite intelligible to the candid mind. Newton had a 

 fine faith in his reader. He gave the Definitiones and 

 Axiofnata in a form that appealed at once to the common 

 experiences of thoughtful minds ; and what more do we 

 need 1 



Prof. Pearson characterizes the second law as a 

 "veritable metaphysical somersault. How the imper- 

 ceptible cause of change in motion can be applied in a 

 straight line surpasses comprehension, &c." This may 

 be smart, but is it relevant ? Where does Newton define 

 Vis Motrix as the " imperceptible cause of change in 

 motion " 1 



We have not space to enter upon a discussion of 

 the five laws of motion suggested by Sir Thomas 

 Gresham's Professor of Geometry as a true non- 

 metaphysical basis for all science. They are good 

 enough in their way ; but they seem to lack that direct 

 reference to ordinary facts of experience which is a 

 desideratum of all physical axioms. They begin with a 

 dance of molecules and end with a measure of force 

 Their ostensible merits are their logical form and their 

 comprehensiveness— ether corpuscles as well as matter 

 corpuscles being nominally included. Yet we have to 

 confess our inability to see that these laws of motion 

 can effect more than Newton's. Dynamics, in all its 

 branches, still is Newtonian. 



In its discussion of the meaning of scientific law, in its 

 presentation of kinematic principles, and in its treatment 

 of certain present-day speculations as to the constitu- 

 tion of matter and of ether, Prof. Pearson's book is at 

 once interesting and instructive. There is much in it 

 fitted to arrest the materialistic tendency of many who 

 are devotees of science to the exclusion of all other 

 intellectual activities. Yet its own conclusions are as 

 materialistic as they well can be. The automaton theory 

 of the human will, and the spontaneous generation 

 of life, are articles of its creed. In the second last 

 chapter we are treated to a choice collection of charming 

 dogmatisms. Perhaps the most charming of all is the 

 author's "unwavering belief" that the hitherto un- 

 discovered formulas which are to make history a science 



