August 26, 1910] 



SCIENCE 



211 



But the formula would contain nearly twice 

 as many terms as the one here submitted, and 

 there would be other disadvantages. 



An empirical formula is valuable for pur- 

 poses of interpolation; but it is utterly un- 

 reliable when used for making predictions, or 

 extrapolations. 



The following table gives a synopsis of the 

 results of the United States Census as to 

 population, and it is given mainly for the 

 sake of calling attention to the last column, 

 which affords a basis for making deductions 

 in regard to the future growth of population. 



Growth of Population 



The last column shows that the relative in- 

 crease was practically constant during the first 

 seventy years, commenced to decline at the 

 end of that period and has continued to do so 

 ever since; the decline during the last fifty 

 years having amounted to 15 per cent. The 

 decrease is likely to be more rapid in the 

 future than it has been in the past, since the 

 conditions for an increase of population are 

 not as favorable now as they were in 1860, 

 when there was so much unoccupied land. It 

 seems evident, therefore, that unless agricul- 

 tural methods are improved and the soil made 

 more productive, or unless people become more 

 economical, the population of the country is 

 likely to reach a stationary state in fifty years 

 or less. 



Fr.«k Gilman 



BosToi^, Mass., 

 July 25, 1910 



' Preliminary estimate. 



QUOTATIONS 



SAL.UIIES OF PROFESSORS 



The question of salaries for professors is 

 one which will always be one of the questions 

 most alive at Cornell. The Carnegie fund for 

 retiring aged professors has been of great help 

 in retaining good men up to the time of re- 

 tirement, but at the present time, when in- 

 comes of men in various professions and 

 trades have advanced so rapidly, the salaries 

 of professors have not advanced with the in- 

 creased cost of living. The result is that 

 much of the teaching has to be done by young 

 men on small salaries who are continually 

 looking in a natural way for opportunities to 

 broaden their incomes and fields of usefulness. 

 It is probable that the original intention of 

 furthering investigation, by retiring pro- 

 fessors at a certain time, will be found to 

 miss this particular mark, because research 

 work represents a type of mind quite as much 

 as it represents opportunity. Men who have 

 not done research work in advance of retire- 

 ment are not apt to do any after retirement. 

 Our policy of selecting noted professors from 

 diiierent parts of the world, as Johns Hop- 

 kins has done, accounts for a part of our 

 rapid progress, but we have need for large 

 incomes which wiU attract the men who at- 

 tract students as they do at some of the older 

 institutions of learning in other countries. 

 We need to be able to offer salaries of at least 

 ten thousand dollars per year for men who 

 have proven their ability to command such 

 salaries, no matter whether such men have 

 developed at Ithaca, or at other institutions 

 of learning. In making up a teaching staff 

 of young men who are simply in line for pro- 

 motion on the ground of faithful work, there 

 is always a menace to the character of the 

 teaching, because propinquity is one of the 

 great powers in this world, and if it is more 

 convenient to fiU positions with men who are 

 near at hand, and who wiU accept such posi- 

 tions on small salary, the tendency is always 

 toward filling the teaching staff with a cum- 

 bersome number of men of merit without 

 genius, but it is the men of genius whose 

 names are synonymous with the names of eer- 



