MODIFICATIONS OF FEVER. 811 



modified by climate and season, states of the 

 atmosphere, modes of living, &c. The fevers 

 which prevail in central Africa, Egypt, the East 

 and West Indies, are not more different from 

 each other, than the climates of those regions. 

 The truth is, that there are no two countries in 

 the world in which the climate is precisely the 

 same ; nor is it probable that any two seasons 

 are precisely alike, even in the same countries.* 

 Hence the endless varieties of fever, which are 

 never the same in any two places or seasons. 



* It is true, that the mean annual temperature of the same 

 place is nearly the same for long periods of time, or at least 

 within a very few degrees of a uniform average. At Chiswick, 

 in the vicinity of London, the mean temperature of ten years, 

 (1826 35,) was 50-5; while that of 1838 was only 47-6. But 

 the mean of January 1838 was 28; whereas the average of the 

 same month was 36 during the preceding ten years, and the 

 minimum 10. In 1838, however, it fell 4-5 below 0, or 14 

 lower than it had done for ten years. At the apartments of the 

 Royal Society, the mean of the year 1838 was 48-9, or 1-3 

 higher than at Chiswick. According to Mr. Luke Howard, the 

 mean temperature of London from 1797 to 1819, was 50 '65, 

 while at Tottenham Green, four miles north from town, it was 48-8, 

 making the difference 1 -85. In the third Report of the Registrar 

 General, it is stated by Mr. Farr, that the mean of January, Feb- 

 ruary, and March, 1838, was 36-3 ; and 4-6 lower than during 

 the same period in 1840; while the spring of 1841 was 4-3 

 warmer than that of 1839. And the summer of 1842 has been 

 4'75 warmer than that of 1841 making a very large increase 

 in the products of the soil throughout the United Kingdom. In 

 the United States, the mean annual temperature of the year at 

 Germantown, near Philadelphia, was 49'6 in 1821, and 54-2 

 in 1825, making the difference 4-6. And it is still greater dur- 

 ing different seasons, especially when one winter is compared 

 with others. 



