4 Limits of the Mean Temperature of Years. 



In consequence of these variations, if we compare the ex- 

 treme temperatures of each month with the mean or normal 

 temperatures of all the rest, we shall find : — 



That the month of January is sometimes as temperate as 



the mean of the month of March. 

 That the month of February sometimes resembles the 



mean second fortnight of April, or the mean first fort- 

 night of January. 

 That the month of March sometimes resembles the mean 



of the month of April, or the mean of the second fort- 

 night of January. 

 That the month of April never reaches the temperature of 



the month of May. 

 That the month of May is pretty frequently, in the mean, 



warmer than certain months of June. 

 That the month of Jurie is sometimes, in the mean, warmer 



than certain months of July. 

 That the month of July is sometimes, in the mean, warmer 



than certain months of August. 

 That the month of August is sometimes, in the mean, 



slightly colder than certain months of September. 

 That the month of September is sometimes, in the mean, 



colder than certain months of October. 

 That the month of October may be, in the mean, nearly 3^ 



(5°'4 F.) colder than certain months of November. 

 That the month of November may be, in the mean, about 



5°-5 (about 10° F.) colder than the warmest months of 



December. 

 That the month of December may be, in the mean, 7° 



(12°-6 F.) colder than the month of January. 



Disturbing causes of Terrestrial Temperature which cannot be 

 foreseen. 



The atmosphere which, on a given day, rests upon the sea, 

 becomes in a short time, in mean latitudes, the atmosphere 

 of continents, chiefly from the prevalence of westerly winds. 

 The atmosphere derives its temperature, in a great measure, 

 from that of the solid or liquid bodies which it envelops. 

 Every thing, therefore, which modifies the normal tempera- 



