CLIMATE AND HEALTH 79 



summers are warm enough so that there is a considerable period 

 when the thermometer approaches 70° at noon. Such conditions 

 apparently prevailed in the region where our ancestors acquired 

 their present adaptation to climate. 



In this connection a curious fact should be noted in respect to 

 the negroes. For sixteen months Miss Ellen Cope, Mr. H. S. 

 Williams, and some of the other teachers at Hampton Institute 

 carried on a series of tests under the direction of the author. 

 Eleven young men and eleven young women, all being negroes 

 ranging from seventeen to twenty-five years of age, were given 

 daily tests at a set hour under highly uniform conditions. Their 

 physical strength was tested by pressing a dynamometer ten times. 

 Their mental activity was tested by placing letters in the proper 

 order on some prepared boards and by the common test of striking 

 out letters on a printed sheet. The test with the boards proved 

 much the more satisfactory. At the beginning of each test each 

 scholar had before him a board with a series of compartments 

 arranged in horizontal rows of seven. On the left of these the 

 various letters of the alphabet were placed in piles arranged 

 differently each day so that it was impossible to learn any par- 

 ticular arrangement. After the pupils had been called to atten- 

 tion, the teacher slowly read five letters, started a stop-watch 

 and let it run a minute. The pupils had to remember the order 

 of the letters, which proved to be a fairly severe memory test; 

 find them among the piles on their left; and place them in the 

 proper order in the little compartments as many times as pos- 

 sible. At the end of a minute the teacher called time, read a new 

 set of letters, and the work was repeated. This was done five 

 times each day. 



These tests involved a physical factor, namely, the speed with 

 which the pupils moved their hands, but they involved to an equal 

 or higher degree the mental factors of attention and memory. 

 Reason, however, was not involved. Hence I do not feel sure 

 whether the results show a real mental difference between the 



