64 A COMPARISON BETWEEN THK 



current of malaria, may sometimes be moving in a direction different 

 from that in which the wind may happen to be blowing. 



The following is a summary of the results of the foregoing com- 

 parison : whether they are applicable to a series of years must be 

 determined by a more extensive set of observations. We have little 

 doubt of their correctness, not only for the year which has passed in 

 review, but generally. 



TEMPERATURE. 



I. — During the summer the mean temperature of London is about 

 5° higher than at IMalvern ; an effect attributable partly 

 to the greater power and influence of the sun's rays among 

 crowded buildings and paved streets than in the open coun- 

 try, and to the elevation of the latter place. 



2. — In autumn the mean temperature of London is 2J higher 

 than at Malvern ;-^attribu table to the causes mentioned in !• 



3. — During the winter months the mean temperature of London 

 and Malvern varies only ^^ of a degree, and the difference 

 in the mean range of the thermometer during the season 

 is only about J a degree. The sun's rays are so feeble at 

 this season, and the maximum of the thermometer being 

 almost invariably due to clouds or warm vapours, the tem- 

 perature becomes more equalized. 



4. — In s])ring the mean temperature of London is 2° higher than 

 at Malvern ; the difference commencing in the month of 

 April, when the power of the sun's rays is becoming deve- 

 loped, as staled in 1. 



MEAN TEMPERATURE OF THE YEAR, 



AS ASCERTAINED IN THE FOREGOING COMPARISON. 



London 62° 



Great Malvern 49.6 



The mean temperature of London, derived from observations con- 

 tinued for three successive years, by Mr. Daniell, and embracing the 

 daily maxima and minima, is 49.5. 



