244 R. D. Thomson, Esq., on the 



The mean height of the barometer, corrected, for the year, was 

 29 742 inches, and reduced to the level of the sea, 29-892 inches ; 

 this very nearly approaches the usually-assumed barometric pressure 

 at the sea-level, or 29*92 mches, the difference being only xo o o •" 

 deficiency as respects the year. The pressure of dry air at the level 

 of the sea, would be 29-581 inches. The pressure of vapour in the 

 air during eleven months, was -284 inch, and the vapour in a cubic 

 foot of air 3"26 grains. The total fall of rain was 31-24 inches; 

 the mean of five preceding years being 34-04, and of six years, in- 

 cluding the present, 33-6 mches. The number of days on which 

 rain fell was 180, giving an average of nearly 3| days per week; 

 the greatest number of rainy days being in January, and the least in 

 September. The greatest height of the barometer during the year 

 was 30*503 inches, on the 28th December, or at the level of the sea 

 it would have stood at 30-653 inches. It was remarkable that at 

 this period, when the barometer was considerably above 30 inches, 

 the atmosphere was generally obscured by thick fogs and by frequent 

 drizzle, with the wind from the S. and SE. The lowest depression 

 of the barometer was 28-736, on the 14th July, with a S. wind, 

 accompanied with a fall of rain ('61) upwards of half-an-inch in 

 depth in twenty-four hours. The range of the barometer has there- 

 fore been 1-897 inches. 



The distribution of the temperature of the year has been somewhat 

 irregular. The month of January was remarkably mild, the mean 

 heat being 4r*5 or about 7° above that of the year 1850 (34°*3) ; 

 and notwithstandincr the wetness of the season, the first two months 

 of the year were not unfavourable to health. The mean tempera- 

 ture of the first half of the year was 45°* 3, of the second half, 49°*5, 

 and the mean of the whole year, 47°'4 — a number considerably 

 higher than could be anticipated from the latitude. It remains to 

 be ascertained, by future observations, whether the excess of tem- 

 perature over calculation is dependent on local causes. The mean 

 temperature to the west of the city, during the year 1850, was found 

 by Mr James King, at 9 a.m., 47°'6, and at 9 p.m., 47°-7 ; and by 

 applying the Greenwich corrections, these numbers become a mean 

 of 48°, affording a close approximation to the results of the present 

 year. The instruments were compared with the Greenwich standard. 



The highest temperature attained during the summer was 82°*4, 

 on the 30th June, and during ihe two preceding days the maximum 

 thermometer reached 80°*6 and 81°*1, — a rare circumstance in this 

 latitude. The highest heat at Greenwich Observatory, at the same 

 period, was 87°, with a westerly wind. The lowest teniperature of 

 the year was 25°*9, on the 3d December, making a. difference in the 

 extremes for the year of 56°* 5. The connection of the temperature 

 with the mortality, in the different months, will be best observed by 

 constructing a table on the following plan : — , 



