THE INFLUENCE OE CLIMATE. 93 



contingent that was employed in the English army paid a 

 heavy tribute to death.* On the contrary, official documents 

 for 1861 tell us that, at Sierra Leone, f the respective mor- 

 tality of English and Negro soldiers was as follows : 



Deaths per 1000. 

 English. Negroes, 



Marsh fevers ... - 410-2 ... 2.4 

 Dysentery 41-3 ... 5-3 



Liver disease - - - - 6'0 ... 1*1 



It is an indubitable fact that, in general, the mortality of an 

 emigrated population is in an inverse ratio to the distance they 

 are taken. J During many years the island of Ceylon was 

 occupied by Hindu troops (from Madras and Bengal), Malays, 

 Negroes and English. The mortality of these races respec- 

 tively was, 12, 24, 50, and 69. 



This is so clearly a biological law, that we again meet with 

 its application even in certain particular cases. Concerning 

 the yellow fever, for instance, Townsend has thus laid down a 

 rule, (( The mortality to the new-comer from the cooler lati* 

 tudes may be said to be in an exact ratio to the distance from 

 the equator of his place of nativity ." Daniel Blair || has 

 given the following statistics, according to his observations of 

 the same disease, made in British Gruiana, from 1827 to 1835 : 



Natives (West Indian Islanders) ... 6.9 



French and Italians - - - - - - 17'1 



English, Scotch, and Irish - 19'3 



Germans and Dutch ------ 2O2 



Scandinavians and Eussians - 27'7 



* It would appear from the documents collected by Nott (Two Lectures on 

 the Natural History of the Caucasian and Negro Races, Mobile, 1844, com- 

 pare Boudin, Geogr. Med., vol. ii, p. 144), that as we advance towards the 

 upper part of the Northern States, madness becomes very frequent among 

 the Negroes. It reaches the proportion of one case of insanity among 

 twenty-eight sane persons in Massachusetts and Maine. ' We hesitate in ac- 

 knowledging climateric influence, because the number of cases seems to 

 increase relatively to the degree of instruction among the people ; not that 

 madness depends on education, but because it finds out a great number of 

 cases of which we should otherwise have been ignorant, as often happens in 

 the east among a less enlightened people. 



f Compare Boudin, Bulletins de la Socie'te' d' Anthropologie, August 1, 1861. 



j Compare Boudin, Traite de Geographic Medicale, 1857, Introduction. 



New York Medical Journal, p. 399, February 1831 (see Hirsch, Handbuch 

 der Historisch-geographischen Pathologic, 35, p. 1). 



|| Some Account of the Last Yellow Fever Epidemic of British Guiana, p. 59, 

 8vo, London, 1850. 



