during the Quarter ending December SI, IS-iS. 183 



21st the temperature was 4°*5 below the average ; on the 18th 

 it was 10° in defect. From October 22 to October 30 it was 

 5°*3 in excess; the greatest was 7''7 on the 27th. From 

 October 31 to November 16 the temperature was mostly be- 

 low the average, its mean defect was 4<°'2, its greatest within 

 the period was 10°*2 on the 4th. From November 17 to 

 December 19 the temperature exceeded the average by 4°'8, 

 On December 7 the excess was 12°'4 ; on the 8th was 15°*7; 

 on the 9th was l^^-'i; and on the 10th was 10°'l. From 

 December 20 to December 24 the defect was 6°*2 ; from 

 December 25 to December 29 the excess was 5°*8 ; and it 

 was 2° '3 below the average on December 30 and 31. The 

 following are the particulars of each subject of investigation 

 arranged as in the preceding quarters. 



The mean temperature of the air at Greenwich — 



For the month of October was 51°-6, which is 2°-5, 6°'2, 

 3^-6, 2°-l, 1°'4, and l°'l aioue those of the years 1841 to 1846 

 respectively, and 1°*3 beloiio ihat in the year 1847; oritis2°-3 

 above the average of these seven years ; 



For the month of November was 43°'8, which is l°'l and 

 1°*0 above those of the years 1 841 and 1842, of the same value 

 as that of 1843, 0''-2, 2°-0, 2°-2, and 3°-l below those of the 

 years 1844 to 1 847 respectively ; or it is 0°'7 below the average 

 of these seven years; 



For the month of December was 44°'0, which is 3*^*5, 0°'l, 

 ll°-0, 2°-3, 11°-1 and l°-2 «Z»ot;e those of the years 1841, 1843, 

 1844, 1845, 1846, and 1847 respectively; and \°'Obelow that 

 of the year 1842, or it is 4°"1 above the average of these seven 

 years. 



The mean value for the quarter was 46°"5; that for 1841 

 was 44°-0; for 1842 was 44°-4 ; for 1843 was 45°-2 ; for 1844 

 was 42°-2; for 1845 was 45°-9 ; for 1846 was 43°'l ; and for 

 1847 was 47°*5 ; so that the excess of temperature this quarter 

 above the corresponding quarter in the years 1841 to 1846 

 was 2°'5, 2°'l, l°-3, 4°-3, 0°-6, and 3°-4 respectively ; the only 

 year between 1841 and 1847 whose mean temperature for this 

 period was ^r^a^£?r than that for the present year was 1847, 

 and the difference is 1°'0. The average value for this quarter 

 from the seven preceding years was 44°*6 ; so that the mean 

 temperature of the air for the quarter ending December 31, 

 1848, was above that of the corresponding quarter in the pre- 

 ceding seven years by 1°'9. 



The mean temperature of evaporation at Greenwich — 



For the month of October was 49^*3, which is 1°'5 above 

 that for the preceding seven years ; 



For the month of November was 41°*7, which is 1°'7 below 

 that for the preceding seven years; 



