Januaey 2, 1903.] 



SCIENCE. 



11 



mentioned in the many estimates that have 

 been made of the value of science study in 

 education, for as a matter of fact that 

 complete definiteness which is usually 

 urged as the characteristic feature of sci- 

 ence study is the fundamental condition 

 of every psychological process; you say 

 this or you say that, you go or you do not 

 go; and the psychological processes which 

 play in the study of science do not differ 

 from other psychological processes in this 

 respect, absolutely not at all. 



Let me illustrate this objective character 

 of science study by an example which hap- 

 pens also to illustrate an error which I 

 suppose many of you entertain. What is 

 the definition of the mass of a body? The 

 careless and imaginative definition which 

 is usually given is that ' the mass of a body 

 is the quantity of matter the body con- 

 tains.' I suppose that definition satisfies 

 many of you, but it does not satisfy me. 

 All our notions of length and angle take 

 their rise in and are fixed or defined by 

 those fundamental geometric operations of 

 congruence. The real definition of mass 

 is no less a physical operation, the verbal 

 definition is the briefest possible specifica- 

 tion of this operation and it can be nothing 

 else, the result of this operation on a given 

 body is an invariant number, and by a feat 

 of the imagination we conceive this inva- 

 riant number to be a measure of the quan- 

 tity of matter the body contains. Ask a 

 farmer's boy how he would define or set 

 the boundaries to a cow pasture, explain- 

 ing to him that you seek real practical in- 

 formation, and I think he could only 

 answer, by building a fence around it! 

 Most of our definitions in physics which 

 apply to sensible things are necessarily ap- 

 plied to ideally simplified conditions which 

 can not be feasibly realized as actual opera- 

 tions, all for the sake of simplicity and 

 directness of statement, and the conse- 

 quence is, I think, that many of us lose 



sight of the fact that these definitions are 

 in reality operations. 



I sometimes think that no popular sci- 

 entific writings should be tolerated which 

 do not introduce the reader to some ap- 

 preciation of the exacting requirements of 

 successful work. Some of Jules Verne's 

 stories, for example, are peculiarly faulty 

 in this respect, and these stories, and many 

 others like them, are largely responsible, 

 in my opinion, for the widespread fancied 

 interest in science on the part of those who 

 really care only for its immediate results. 

 Most persons are fascinated by Jules 

 Verne's care-less trip to the moon and by 

 the easy improvidence of his ten thousand 

 leagues under the sea. 



A short time ago I had occasion to re- 

 view a little book in the pages of Science, 

 and I found therein an opportunity to 

 briefly state what in my mind is a more 

 serious perversion of science than that 

 which is presented by those whose fancied 

 interest in it is based on its results, and 

 who, poor fools, invest in Keeley motors 

 and sea gold companies because, forsooth, 

 the desired result is so clearly evident. 

 Surely one can not hold the 'scientific 

 spirit' accountable for 'great degener- 

 acies' like these. The book in question 

 purports to treat of the atomic theory, it 

 is prefaced by an introduction by a pro- 

 fessor in the University of Chicago, and 

 it deserves a place in DeMorgan's 'Budget 

 of Paradoxes.' I mentioned in my review, 

 to begin with, a list of headings to serve 

 to indicate to the general reader the pres- 

 ent scope of the atomic theory; the atomic 

 theory of gases, the theory of crystal struc- 

 ture, the molecular theory of elasticity, 

 the electro-atomic theory of radiation, the 

 corpuscular theory of the electric discharge 

 and of the electric current, stereo-chem- 

 istry, and the like, and I expressed it as 

 mv conviction that neither the author nor 



