482 



SCIENCE. 



[N. S. Vol. XIX. No. 482. 



But change does not always spell ad- 

 vance, and not every novelty is an im- 

 provement. It may be well, therefore, 

 before we consider progress along any par- 

 ticular line, to recall what constitutes prog- 

 ress in general. The profound studies of 

 Mr. Spencer led him to a very happy defi- 

 nition of progress, namely, 'an increase in 

 the adaptation of man to his environment. ' 

 This description would be eminently satis- 

 factory were it not that in another place 

 Mr. Spencer characterizes progress as a 

 'benevolent necessity,' thus robbing it of 

 every element of hviman initiative and of 

 conscious endeavor. For this reason many 

 of Mr. Spencer's most ardent admirers— 

 among whom I count myself — while ad- 

 mitting the happiness of his phrasing, will 

 nevertheless prefer the view of Professor 

 Karl Pearson who regards progress as the 

 result of a distinct program, the outcome 

 of plans laid with care and according to 

 the soundest biological principles. 



Having in mind this point of view from 

 which progress is a consequence of delib- 

 erate forethought, I invite your attention 

 to some of the advances recently made in 

 the teaching of physics to English-speaking 

 students. 



Let us use the word 'recently' as refer- 

 ring to the last thirty years and consider 

 first some advances in the teaching of 

 physics which have resulted from advances 

 in the science of physics. 



I. IMPROVEMENTS IN MATERIAL. 



The purchase by Princeton College of 

 one of the Gramme machines exhibited at 

 the Centennial Exposition in 1876 may, 

 perhaps, be fairly considered as marking 

 the introduction of the modern dynamo 

 into the American physical laboratory. 

 Only five years after this date I found 

 myself a student in this laboratory which 

 had purchased the Gramme machine— an 

 excellently equipped and ably directed 



laboratory, then as now. A single illustra- 

 tion must suffice to show how matters have 

 changed. On turning the pages of my first- 

 year note-book, I find that one of the ex- 

 periments assigned me was the measure- 

 ment of the current furnished by this 

 Gramme machine under certain definite 

 conditions. This was done in two ways: 

 (1) the earth's horizontal magnetic com- 

 ponent was determined at a certain point; 

 at this particular point was placed a tan- 

 gent galvanometer whose constant I had 

 computed ; the deflection which the current 

 produced in this instrument completed the 

 data necessary to determine the current in 

 webers. Amperes were yet novelties, not 

 to say mysteries. The graded galvanometer 

 and the ampere-balance of Kelvin were not 

 yet on the market. The beautiful instru- 

 ments of Weston were unknown. (2) The 

 second method employed was to assume the 

 electro-chemical equivalent of copper and 

 proceed to measure the average current by 

 weighing the amount of metal which it had 

 deposited. 



Each of these processes proved highly 

 instructive, and they are cited merely to 

 show the amount of time and detail which 

 the student was driven to consume when 

 for any reason he wished to know the value 

 of the current he was using ; for the ' work- 

 ing constant' of the galvanometer carried 

 about the laboratory was by no means so 

 constant as its name might imply. 



Another forward step was marked by the 

 introduction of the low-resistance, portable 

 D'Arsonval galvanometer which permits 

 the elementary student, at his own labora- 

 tory table, to study practically all the 

 fundamental properties of electric cur- 

 rents ; this with an outfit which is sim- 

 plicity itself, and at a cost which brings 

 the entire equipment easily within the 

 range of the most modest high school. The 

 point here, let me insist, is not the increased 

 convenience and comfort of the student, 



