368 Mr. J. Glaisher's Remarks on the Weather 



For the month of February was 4'3°'2, exceeding the ave- 

 rage of the preceding seventy years by 4°'7. The temperature 

 of this month in the year 1779 was 45°*2, being the only in- 

 stance within the period of seventy years in which the tem- 

 perature exceeded that of this year; 



P^or the month of March was 42°'5, exceeding the average 

 of seventy years by l"'2. 



The mean for the quarter was 41°*9. The average value for 

 seventy years is 38°'6. In the year 1779 the mean was 4?2°*0 ; 

 in 1822 it was 43°-4; in 1834 it was 42°-S; and in the year 1846 

 it was 43^*6 : in all the remaining years it was less than 42°'0. 



The excess of temperature above the average of the prece- 

 ding eight years was in January 3°'0; in February was 5°'4; 

 in March was 0°'l ; and for the quarter was 2°*9. 



The mean temperature of evaporation at Gree7iwich — 



For the month of January was 38°'6 ; for February was 

 41°*4 ; and for March was 39°'8. These values are 2°*0 above, 

 6°'-2 above, and 0°*3 beloio, respectively, the averages of the 

 preceding eight years. 



The mean value for the quarter was 39°*9, which is 2°'6 

 above that of the average of eight years. 



The mean temperature of the dew-point at Greenwich — 



For the months of January, February and March, were 36°'4, 

 38°'8, and 36°'5. The average values for the preceding 

 eight years were 35°- 1, 34°-5, and 36°-6. 



The mean value for the quarter was 37°'2, which is 1°*8 

 above the average for the preceding eight years. 



The mean elastic force of vaponr for the quarter was 0*239 

 inch, which is 0*012 inch greater than the average for the pre- 

 ceding seven years. 



The mean 'weight of *water in a cubic foot of air for the 

 quarter was 2*8 grains, which is 0*1 grain greater than the 

 average of the preceding seven years. 



The mean additional weight of water required to saturate a 

 cubic foot of air was 0*6 grain. This value for the preceding 

 seven years was 0*38 grain. 



The mean degree of humidity in January was 0*883, in Fe- 

 bruary was 0*863, and in March was 0*801. The averages 

 for the seven preceding years were 0*903, 0*888, and 0*841. 

 The mean value for the quarter was 0-849, which is 0*028 less 

 than the average for these years. These values denote a con- 

 siderable degree of dryness in these months. 



The mean reading of the barometer at Greenwich in January 

 was 29*771 inches, in February was 30*106 inches, and in 

 March was 29*915 inches; these values are 0*005 inch above, 

 0*415 inch aioi'f, and 0*186 inch aiow respectively the averages 

 of the same months for the preceding eight years. 



