August 30, 1919] 



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man or sophomore year, and the interval of 

 two or three years until research is begun 

 blots out much of what was actually learned. 

 Consequently, when the student has arrived at 

 the research stage he must, with much loss of 

 time and with much eilort, rediscover methods 

 and devise artifices which perhaps are well 

 known in physical technique. 



We must conclude that if the physicist has 

 realized the fact that so many measurements 

 are essentially physical, and that it would 

 mean much for progress in all branches of 

 science if those engaged in scientific research 

 of any kind had at their command more 

 physics, he has been at fault in not sufficiently 

 emphasizing these facts and in not offering 

 such a sequence of courses in physics as would 

 recognize them. 



Bearing in mind that the time which could 

 be apportioned to such work would probably 

 at best be limited, I should say that, in addi- 

 tion to the regular course in general physics, 

 there should be offered a course, preferably 

 during the senior year, which might be 

 designated " chemical and biological physics." 

 Such a course should be planned to give 

 the student who contemplates graduate work, 

 as well as the student going out into indus- 

 trial work after his graduation, those prin- 

 ciples and measurements which are known to 

 be fundamental in the kinds of work that 

 might be expected to follow. I should plan to 

 have such a course occupy at least the equiv- 

 alent of three two-hour periods for one semes- 

 ter of sixteen weeks. The following general 

 topics might be taken as representing the 

 essential things from which as many might be 

 selected as were considered advisable, accord- 

 ing to circumstances. (1) The accurate meas- 

 urement of long and short time intervals. 

 (2) Measurement of temperatures by methods 

 other than the mercury thermometer. Prin- 

 ciples of pyrometry. (3) Temjwrature regula- 

 tion and temperature regulators and con- 

 trollers. (4) Principles of precision calori- 

 metry. (5) The microscope; its theory, and 

 application to the measurement of small 

 lengths. (6) The reading telescope and its 

 application to the measurement of small 

 angles. (7) Measurement of refractive in- 



dex ; spectrometer and refractometer. (8) The 

 spectroscope, and spectroscopic analysis. (9) 

 Color and colorimetry; intensity of light and 

 photometry. (10) The polariscope and polari- 

 meter. (11) The galvanometer; its use as a 

 deflection and as a null instrument. (12) 

 Ohm's law; measurement of current and 

 potential differences. (13) Electric power 

 and heating. (14) Resistance measiirement ; 

 Wheatstone's bridge, with application to 

 measurement of electrolytic conductivity. 

 The alternating current galvanometer as 

 applied to conductivity measurements. (15) 

 The potentiometer; application to measure- 

 ment of thermoelectric forces, electrode po- 

 tentials, ionic concentrations. (16) Electro- 

 meters and electroscopes; applications to 

 measurements in radioactivity. (17) Prin- 

 ciples of X-ray measurements. 



Fortified with the essentials of such a 

 course, the student would be well grounded 

 for the physics of almost any problem of re- 

 search he might meet. Certainly the " gen- 

 eral physics " course wotdd fall short of 

 giving him anything more than a somewhat 

 hazy idea of the instruments mentioned in the 

 above list, and of the purpose for which they 

 are used. 



Putting this work in the senior or first post- 

 senior year would have the effect of attracting 

 students who have come to realize the im- 

 jKirtance of these things in relation to their 

 future work. A well-defined motive is much 

 to be desired in any course, and, such a motive 

 existing, the course should prove very success- 

 ful from the viewpoints of both student and 

 instructor. 



Some of the measurements above mentioned 

 are described — not at all adequately — in man- 

 uals of physical chemistry; but there the ob- 

 ject of the experiment is the result, not the 

 theory or technique of the measurement. The 

 logical place for such a course is in the phys- 

 ics department, by an instructor who has thor- 

 oughly familiarized himself with the student's 

 needs, and who knows what applications may 

 later be expected of the kinds of measure- 

 ments he teaches. Such an instructor, I dare- 

 say, would render a valuable service to his 

 colleagues in the other sciences in the capacity 



