i 4 8 THE POPULAR SCIENCE MONTHLY. 



his last chapter is devoted to showing that this theory is itself a failure, so that, 

 when he takes his leave, we have nothing left to contemplate hut a mass of ruins. 



It is curious to note the introduction of the word " seems " into this 

 passage as the lawyers say, its appearance with a semble while in 

 other places, e. g., where Professor Newcomb speaks of the proposition 

 that molecules are inelastic as my "favorite doctrine," or where he 

 charges me (after reading my tenth chapter !) with ignorantly con- 

 founding the "abstract noun" mass with the concrete term matter, he 

 makes no such qualification. 



Having satisfied himself (no doubt before writing his article, 

 though the conclusion is stated most explicitly toward its close) that I 

 am in the lists as a champion of the atomo-mechanical theory and as 

 the dogmatic defender of its fundamental propositions, he proceeds to 

 assail these propositions, sometimes with what he seems to regard as 

 an argument, but generally with a sneer. The contents of my intro- 

 ductory chapter, consisting almost exclusively of citations from the 

 writings of Professors Kirchhoff, Helmholtz, Clerk Maxwell, Ludwig, 

 Du Bois-Reymond, etc., he brands as "propositions in which we can 

 trace neither coherence nor sense." The thesis that, on the basis of the 

 atomo-mechanical theory, all potential energy is in reality kinetic 

 the distinct proposition of Professor P. G. Tait, who asserts it as the 

 unavoidable consequence of the atomo-mechanical theory of gravita- 

 tion he "passes over as not even worth quoting." Similarly the doc- 

 trine of the essential passivity of matter also a proposition of Pro- 

 fessor Tait, whose exact words I quote on page 306 of my book is 

 flouted with the disdainful remark that " such words as * active ' and 

 ' passive' have no application in the case and serve no purpose, except 

 to produce confusion in the mind of the reader." In this way he 

 levels his thrusts at the most eminent physicists and mathematicians 

 of the day, laboring always under the hallucination that he is strik- 

 ing at me. 



Among the most characteristic performances of Professor New- 

 comb are his strictures, already adverted to, on my substitution of the 

 term mass for the word matter, in designation of the substratum of 

 motion in the light of the atomo-mechanical theory. According to 

 him, this use of the word mass is evidence of my ignorance and intel- 

 lectual confusion, as well as of my " total misconception of the ideas 

 and methods of modern science." He informs me that the word mass 

 is " an abstract noun like length" whereas I use it " as a concrete term, 

 and in nearly the same sense as we commonly use the word matter." 

 And thereupon he delivers himself of a dissertation (which resembles 

 nothing so much as a sermon of " Fray Gerundio " to his " familiars ") 

 on the necessity of using scientific terms only in accordance with their 

 exact definitions, of ascertaining the meanings of the words mass and 

 motion by a reference to the methods whereby they are measured, and 



