June 12, 1914] 



SCIENCE 



881 



on the Pearson scale. In other words, on the 7 

 per cent, basis of excellence, the grade " excel- 

 lent " is easier to reach in a small class than 

 in a large one. If a class is divided arbitrar- 

 ily into four groups, equal in number, as in 

 the Missouri system, then the lower limit of 

 merit for the top group is .6588 for a class of 

 100, .6368 for a class of 40, and .5972 for a 

 class of 20. Twentj'-five per cent, of a class of 

 51 members is 13, but only 12 of these have a 

 mark above .6588 on the Pearson scale. Such 

 variability of standards does violence to our 

 sense of scientific rigor, though the practical 

 results do not usually differ, owing to the fact 

 that in practise only integral numbers apply. 



In a scientific marking system the first 

 requisite is uniformity of standards of refer- 

 ence. Lack of uniformity is snfficient reason 

 for rejecting the classification into groups on 

 the percentage basis, as in the Missouri sys- 

 tem and others, unless that basis has some ad- 

 vantages which compensate for its theoretical 

 defects. Such advantages it is difiicult to dis- 

 cover. 



To summarize, our proposed plsn of mark- 

 ing is as follows : 



1. A system of preliminary marking is used, 

 merely to determine the rank of the students. 



2. After the rank is fixed, each student is 

 assigned the marks given in our table, with 

 such slight modifications of the marks as are 

 necessary in the judgment of the instructor. 



The advantages of this system are : 



1. It rests upon correct statistical theory. 



2. The groups called " superior," " medium," 

 " inferior " cover equal ranges of ability. 

 These ranges are constant, no matter what 

 the size of the class may be. Neither the top 

 group called " excellent," nor the bottom 

 group called " poor " has a fixed extreme 

 limit, thereby providing, as the system should, 

 for the grading of men of genius at one end 

 and of the intellectual sluggards at the other. 



3. It tends to eliminate the personal equa- 

 tion of the examiner. 



4. The method is absolute, except in the de- 

 termination of the deviations of the marks of 

 a class from the average marks of classes of 

 that size. 



" This is a complicated system," you will 

 say. So it is, though not quite so complex, 

 perhaps, as it appears at first sight. Chemists 

 and physicists know that any process of ex- 

 act measurements requires time, patience and 

 skill. That is true of our plan. 



Florian Cajori 

 Colorado College, 

 Colorado Springs 



AMJESICAN ASSOCIATION FOB THE AD- 

 VANCEMENT OF SCIENCE 



SECTION B — PHYSICS 



Section B — Physics — of the American Associa- 

 tion for the Advancement of Science held its 

 meetings jointly with the American Physical So- 

 ciety during the convocation week beginning De- 

 cember 29, 1913, at the Georgia School of Tech- 

 nology. 



Professor Anthony Zeleny, of the University of 

 Minnesota, was elected vice-president of the sec- 

 tion for the ensuing year. There were also elected 

 to the Sectional Committee, Professor D. C. JMiller, 

 Case School of Applied Science, 4 years, and Pro- 

 fessor G. W. Stewart, University of Iowa, 5 years. 



As customary in the past all the shorter and 

 more technical physical papers were given under 

 the auspices of the American Physical Society. 

 On the other hand the longer papers, and, in this 

 case, those that dealt especially with geophysical 

 problems, were grouped together and given under 

 the auspices of Section B. These were: 



The Methods of Physical Science, to What are 

 They Applicable?: Aethur G. Webster. 

 This was the vice-presidential address, and is 



given in full in Science, 39, pp. 42-51, 1914. 



The Present Status of the Magnetic Survey of the 



Earth: L. A. Bauer. 



A concise summary was given in this paper of 

 some of the more important investigations under- 

 taken, and conclusions reached, by the department 

 of terrestrial magnetism of the Carnegie Institu- 

 tion of Washington. The great progress of the 

 magnetic survey of the earth, as conducted by this 

 institution, both over land and over water, was 

 shown on a projected map. Many thousands of 

 miles, even hundreds of thousands, have been tra- 

 versed in obtaining the data necessary to the ac- 

 curate magnetic mapping of the earth; nor were 

 the routes followed along the safe and beaten 

 tracks of travel, but rather across the least fre- 



