548 



EVOLUTION OF HEAT, LIGHT, AND ELECTRICITY. 



the iufant becomes more independent of it as development advances, it is 

 many years before the standard can be maintained without assistance, 

 throughout the ordinary vicissitudes of external temperature. Especial care 

 is required with regard to the maintenance of the bodily heat by artificial 

 warmth, in the case of children 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 mouth, it has not been found possible to maintain the warmth 

 of the iufant by exposure to the radiant heat 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 para- 

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

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

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



440. 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 recorded 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 ex- 

 ternal temperature has a very marked influence ; for the average mortality 

 during each of the three summer mouths being 80, that of January is nearly 

 140, and the average of February and March is 12"). This is confirmed by 

 the result obtained by MM. Villcrme and Milne-Edwards, in their researches 

 on the mortality of the children conveyed to the Foundling Hospitals in the 

 dilK'rent 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. 2 As childhood advances, however, the winter mortality di- 



1 Essai de Physique Sooiale, torn, i, p. 197. 



2 Dr. Emerson lias shown that, in the Southern and Middlo States of North 

 AiiK'rira, the h'njh muinner temperature is the greatest cause of Infant mortality : the 



