128 BULLETIN OF THE 



sent may be summarily dismissed as the mere exhibition of an 

 unprofitable mental captiousness.* 



The kinematist repudiating any attractive force in nature would 

 explain the strong cohesion of matter by the hypothetical external 

 pressure of a hypothetical surrounding fluid. The Plumian pro- 

 fessor of astronomy and physios in the University of Cambridge — 

 James Challis — (a successor of Roger Cotes and of George B. Airy) 

 has declared " the fundamental and only admissible idea of force 

 is that of pressure, exerted either actively by the sether against the 

 surfaces of the atoms, or as re-action of the atoms on the aether by 

 resistance to that pressure." f And the professor of physics in the 

 University of Edinburgh — Peter G. Tait — having also relegated 

 the source of all material energy to the action of the highly attenu- 

 ated matter diffused through space, thinks it probable that " force " 

 has no existence, excepting as a convenient expression of a mere 

 rate of transference of kinetic energy.^ 



* " The existence of atoms is itself an hypothesis, and not a probable one. 

 - - - All dogmatic assertion upon such points is to be regarded with dis- 

 trust." (.4 Manual of Inorganic Chemistry, By Charles W. Eliot and 

 Frank H. Storer. 2d edition, revised, New York, 18G8: chap, xxv, p. 605.) 

 And yet these negative dogmatists have not shown themselves capable even 

 of thinking of so elementary a fact in their science as " polymerism " apart 

 from the terms of the atomic conception. As Prof. J. Clerk Maxwell 

 has well observed, "The theory that bodies apparently homogeneous and 

 continuous are so in reality, is in its extreme form a theory incapable of 

 development. To explain the properties of any substance by this theory is 

 impossible." (Encyclopaedia Britannica. 9th ed., 1875: art. " Atom," vol. 

 in, p. 38.) The objection to atomism sometimes urged — that since magni- 

 tude is admitted abstractly or mathematically to be infinitely divisible, 

 therefore any finite particle of matter must also be physically so conceived, 

 — betrays so strange a confusion of ideas as to merit no serious answer. 

 Yet so illustrious a mathematician and philosopher as Leonard Euler was 

 guilty of this gross paralogism. (Letters, to a German Princess. May 3, 

 1761: vol. ii, let. 9.) 



f Principles of Mathematics and Physics. By James Challis. 8vo. 

 Cambridge, 1869 : hyp. v, p. 358. 



Jin an evening lecture on "Force" delivered September 8, 1876, at 

 Glasgow, (during the session of the British Association,) Prof. Tait an- 

 nounced that " there is probably no such thing as force at all ! That it is 

 in fact merely a convenient expression for a certain rate.'" And referring 

 to the corpuscular hypothesis of force, he thought " The most singular 

 thing about it is that if it be true, it will probably lead us to regard all 



