630 



EVOLUTION OF HEAT, LIGHT, AND ELECTRICITY. 



prematurely born ; for the earlier the period of embryonic life, the less is the 

 power of calorification that exists for some time after birth. The temperature 

 of a seven months' child, though well swathed and near a good fire, was found 

 by Dr. W. Edwards, within two or three hours after its birth, to be no more 

 than 89.6. And in some of the recorded instances in which the birth has 

 taken place before the completion of the sixth month, it has not been found 

 possible to maintain the warmth of the infant by exposure to the radiantheat 

 of a fire, the contact of the warm body of another person being the only effectual 

 means of keeping up its temperature. The fullest measure of calorifying power 

 is possessed by adults ; but even in them it is sometimes weakened by previous 

 exertion, so that death by the cooling of the body may occur when the body is 

 exposed to cold of no great intensity, but in a state of exhaustion of nervous 

 power ; a fact which remarkably confirms the views advanced in the preceding 

 paragraph. A decrease of calorifying power takes place in advanced age. Old 

 people complain that their " blood is chill " and they suffer greatly from ex- 

 posure to cold, the temperature of the whole body being lowered by it. These 

 facts have a very interesting connection with the results of statistical inquiries, 

 as to the average number of deaths at different seasons; the following are re- 

 corded by M. Quetelet, 1 as occurring at Brussels, the mean monthly mortality 

 at each age being reckoned as 100. 



We see from this table that, during the first months of infant life, the external 

 temperature has a very marked influence; for the average mortality during each 

 of the three summer months being 80, that of January is nearly 140, and the 

 average of February and March is 125. This is confirmed by the result ob- 

 tained by MM. Villerme and Milne-Edwards in their researches on the mortality 

 of the children conveyed to the Foundling Hospitals in the different towns in 

 France; for they not only ascertained that the mortality is much the greatest 

 during the first three months in the year, but also that it varies in different 

 parts of the kingdom, according to the relative severity of the winter. 3 As 

 childhood advances, however, the winter mortality diminishes, whilst that of the 

 spring undergoes an increase; this is probably due to the greater prevalence of 

 certain epidemics at the latter season; for the same condition is observed, in a 



1 "Essai de Physique Sociale," torn. i. p. 197. 



2 Dr. Emerson has shown that, in the Southern and Middle States of North America, 

 the high summer temperature is the greatest cause of infant mortality; the proportion of 

 deaths during the first year of childhood, occurring in the months of June, July, and 

 August, being about four times greater than that occurring during the same months in 

 any subsequent year up to the age of 20. The winter mortality under the second year 

 scarcely exceeds the average of subsequent years. ("Amer. Journ. of Med. Sci.," Nov. 

 1831.) 



