SUMMARY. 



published in 1847 ; columns 35 to 38 shew, for each result 

 named, the difference between each month and the average of 

 the same month for the five years, and between each year and 

 the average of the five years. The sign + means that the 

 result is greater than the average, and the sign — that the 

 result is less than the average. 



The mean reading of the barometer for the five years was 

 29*860 in. ; the highest reading was 30.862 in., on February 

 11, 1849 ; the lowest 28*382 in., on December 6, 1847. The 

 two latter results shew the state of the barometer on the 

 days named at the ordinary time of reading, but at 1 Oh. p.m. 

 on the last named day the reading was 28*154 in., making 

 the extreme range for the five years 2*708 in. The barometer 

 not being self-registering the true range is probably a little 

 greater. The mean pressure of dry air, reduced to the level 

 of the sea, was 29*580 in. The mean temperature of the air 

 was 49 9°. The highest reading of the self-registering maxi- 

 mum thermometer was 82*3°, on the 19th June, 1846; the 

 lowest reading of the self-registering minimum thermometer 

 was 20*8°, on the 29th January, 1848. The extreme range 

 of temperature for the five years was 61*5°; the mean daily 

 range was 8*8°; the least mean daily range appears to take 

 place in January, when the average is 5*7°, and the greatest 

 in May and June, when the average is 11*8°, The mean 

 annual fall of rain was 28*05 in.; the average number of 

 days in the year on which it fell, 178 ; the largest annual 

 fall was 31*41 in., in 1847 ; and the smallest, 21*46 in., in 

 1850. The mean amount of cloud has been such as to cover 

 6*7 of the sky ; the largest mean amount in any one year, 7*2 

 in 1850 ; and the smallest mean amount 6*3, in 1849. 



The mean temperature of the dew point for the five years 



was 44*9°, just 5° below the mean temperature of the air. 



The mean elastic force of vapour, or the mean amount of 



water mixed with the air, was 0*324 in. The mean weight of 



172 



