158 POPULAR SCIENCE MONTHLY. 



icd. The increase of population is aritlimetically measured, and 

 it stands in relations of direct causation to every social change. 

 The historian, therefore, in forming his judgments of relative in- 

 crease or decrease should always take the increase or decrease of 

 population per square mile as his term of comparison. 



What meaning, finally, shall be attached to the word " great " 

 ■when the historian wishes to distinguish " great " increase or 

 " great " decrease from " increase " or " decrease " in general, and 

 absolute statistics are not available? There is one, and, as far as 

 I can see, only one, perfectly satisfactory procedure. 



Let the investigator subdivide the community which he is study- 

 ing into enumeration units according to the method suggested 

 above for the descriptive monograph. Let him then make as 

 many tables as there are ten-year periods in the general historical 

 period that he is investigating. That is to say, let him make a 

 table for 1850, for 18G0, for 1870, for 1880, and for 1890. Let 

 him then proceed according to the method laid down for the descrip- 

 tive monograph, entering opposite each Commonwealth the symbol 

 for majority or minority, thus showing by States, for each of the 

 ten-year periods, the prevalence of the trait or activity under in- 

 vestigation. Suppose, for example, that the phenomenon studied 

 is the growth of popular interest in prize fighting since 1850. The 

 historian shoiild begin by asking. In what States, if any, in 1850 

 were large majorities of the people interested in prize fights to 

 the extent of countenancing them and eagerly following their 

 progress? In what States w-ere only small majorities so inter- 

 ested, in what States only large minorities, and in what ones 

 only small minorities? The best answers that the historian can 

 make to these questions, after examining all the evidence that he 

 can command, he should record by entering the proper symbol 

 against each State, after which he should repeat the procedure 

 for the date 1860, for the date 1870, and so on. When his tables 

 are thus completed, he should count up the number of entries of 

 each symbol in each table. If then he finds that in less than half 

 of his enumeration units — i. e., in less than half of all the States 

 and Territories — small minorities have become large minorities, 

 large minorities have become small majorities, or small majorities 

 have become large, he will be justified in concluding that there 

 has been an increase, but not a "great" increase, in popular in- 

 terest in prize fighting. If, how^ever, he discovers that these 

 changes have occurred in more than half of his enumeration units, 

 he can say with reason that the increase of interoBt in prize fight- 

 ing has been " great." 



Cases may arise in which a correction of the judgment thus 



