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



nine months ending June 30, 1848, exceeds the average value 

 for the same period of time in the preceding seven years by 

 2°*3. 



The mean temperature of the evaporation at Greenwich — 



For the month of April was 44°*5, which is 0°*4 above 

 that for the preceding seven years ; 



For the month of May was 53°*0, which is 2 0, 6 above that 

 for the preceding seven years; 



For the month of June was 54°*4, which is l°*2 below that 

 for the preceding seven years. 



The mean value for the quarter was 50°*6, which is 0°*6 

 above the average for the seven preceding years. 



The mean temperature of the dew-point at Greenwich — 



For the month of April was 41°*4, which is 0°*7, 3°*1, 0°*8, 

 and 4°*2 above those for the years 1841, 1842, 1845, and 1847. 

 respectively; l°-2, 2°*8, and o, 9 below those of the years 

 1843, 1844 and 1846 j or it is 0°*6 above the average of these 

 seven years ; 



For the month of May was 48°*6, which is 1°*9, 2°*7, 4°*0, 

 and 0°*6 above those for the years 1842, 1844, 1845, and 1846 

 respectively, 2°*2 and 0, 2 below those of the years 1841 and 

 1843, and is the same as that for 1847 ; or it is o, 9 above the 

 average for these seven years ; 



For the month of June was 51°*6, which is 2°-4, 0°*4, 1°*8 

 above those for the years 1841, 1843 and 1847 respectively; 

 2°*7, 3°*6, and 4°*4 below those of the years 1842, 1845 and 

 1846 respectively, and is the same as that for 1844, or it is 

 o, 8 below the average for these seven years. 



The mean value for the quarter was 47°'2, which is 0°*2 

 above the average for the corresponding period of the preceding 

 seven years. 



The mean weight of xvater in a cubic foot of air for the 

 quarter was 3*8 grains, which is 0*1 grain less than the average 

 for the seven preceding years. 



The additional weight of water required to saturate a cubic 

 foot of air was 1 *4 grain. The average for the seven preceding 

 years was 1 *2 grain. The value required in May was 2 grains, 

 and the mean value for May from the preceding seven years 

 is 0°*9 grain only. 



The mean degree of humidity of the atmosphere for April 

 was 0*794, for May was 0*664, and for June was 0*768 ; these 

 values being less than their averages for the seven preceding 

 years by 0*012, 0*154, and 0*01 2 respectively. The value for 

 the quarter was 0*742, which is 0*059 less than the average 

 for these years. 



The mean elastic force of vapour for the quarter was 0*343 



