216 A COMPARISON BETWEEN THE 



In the Report on Meteorology, in the first volume of the British 

 Association, it is stated by the author, that " The errors arising 

 from solar and terrestrial radiation in determining the temperature 

 of a place, have not been sufficiently attended to. It is surprising 

 at what a distance a sensible portion of heat is conveyed from soil, 

 and walls, or even from grass, illuminated by the sun j the maxima 

 of temperature are thus generally too great j and from the near 

 contact in which thermometers are generally placed with large 

 difficultly conducting masses, such as walls, the temperature, 

 during the night, is kept up, and the minima are thus also too 

 high." Such an effect as this may be supposed peculiarly liable to 

 occur in London, where the copious and varied reflections of heat 

 from the pavement, buildings, &c., must, in the bright hot days of 

 summer, considerably increase the maximum of the thermometer j 

 and we find from the foregoing table that the mean maximum 

 range in summer is in London 5.2° higher than in the elevated 

 situation where the village of Great Malvern stands. 



In September, the first month of the autumnal quarter, 

 the mean temperature at Malvern is 4.° lower than the 

 mean temperature in London. The mean maximum at 

 Malvern was 64.° and the mean minimum 49.3.° In Lon- 

 don the mean maximum was 67.3 ° and the mean minimum 

 54.1 ° The maximum height of the thermometer in Lon- 

 don was 74.8° in Malvern, 70 °j the minimum, in London, 

 46.2,° in Malvern, 40. ° The maximum range in London 

 was 28.6° in Malvern, 30.° 



In October, the second month of the autumnal quarter, 

 the mean temperature at Malvern was 2.2° lower than the 

 mean temperature in London. The mean maximum in 

 London was 58.2° and the mean minimum 46.2° In 

 Malvern the mean maximum 56.1° the mean minimum 

 44.3.° The maximum height of the thermometer during 

 the month, in London, was 70.2° the minimum 34.4 °j the 

 maximum, in Malvern, 64.° the minimum, 35.5° The 

 greatest range, in London, 35.8° in Malvern, 28.5 ° 



In November, the last month of the autumnal quarter, 

 the mean temperature of Malvern is 1.7° lower than the 

 mean temperature in London. The mean maximum at 

 Malvern was 47 ° the mean minimum 40.4.° In London 

 the mean maximum was 49.4° and the mean minimum 

 41.4.° The maximum height in London was 61.° in Mal- 

 vern, 59.°; the minimum, in London, 33° in Malvern, 30.° 

 The greatest range, in London, 28.° in Malvern, 29.° 

 In the autumnal quarter, therefore, we have — 



Mean Temperature. Mean Maximum Range. 



London 52.7 ° 30.8° 



Malvern 50. 1 ° 29. 1 ° 



ATMOSPHERIC PRESSURE^ 

 In instituting a comparison between two distant barometers, it 



