158 ALLISON — FLUCTUATION OF THE BAKOMETER. 



of November, at 9 in the morning; — 30.666 — clear with a light 

 west breeze ; and we had a snow storm from east that evening, and 

 a S. E. gale with rain the next morning ; the barometer falling an 

 inch in 18 hours. 30.666 is a high barometer at any time of year 

 in Halifax, but has frequently been exceeded. Notably when we 

 passed under the enormous pressure of 30.956 at 6p.m., of 15 Janu- 

 ary, 1873 ; and again last February 30.992 at midnight of the 5th. 

 It is worth remarking that although we had a stiff S. W. wind and 

 a little snow and rain on the 6th and 7th we got down from this 

 great height without any serious storm. The least pressure of 1875 

 was 28. 601 on the 17th November — only six days previous to the 

 greatest. We have gone below this several times in the last few 

 years; 28.455 on 30th January, 1870, being the lowest. The 

 minimum of last November was in the midst of a rain storm and 

 gale from S. E. to W. Thus we varied 2.065 inches of barometri- 

 cal whole pressure in 1875, oscillating nearly equally on either side 

 of the proper 29.779. 



The mean pressure of vapour was .248 and relative humidity 

 80.71 — elements too often omitted from the consideration of the 

 weight of the atmosphere. The former of these two steadily 

 increased to its maximum of .551 in August, and as steadily fell to 

 the close of the year. The latter was greatest (as is also customary) 

 in July — 84.94 — and the colder months were generally less — though 

 May, with 76.70 was least of all. 



The year was neither very cloudy nor very bright. The mean 

 obscuration of sky was a little over one-half, viz., 5.58. The 

 normal I find to be 5.95. October, with 6.34, was the most cloudy 

 month; and June 4.57 the least so. The summer was more dull, 

 both absolutely and relatively to the normal, than the winter. 



The prevalent direction of our winds from the west quarter was 

 almost constantly marked throughout the year, and the result was 

 nearly due west. A wind east of south not obtaining the supremacy 

 until July denotes the lateness of the spring. These winds from the 

 cooler ocean generally assert themselves in May or June, but their 

 season depends upon the rate at which the water takes in heat. 



The velocity of the wind exceeded the normal rate in each 



