302 ALLISON— NOVA SCOTIAN METEOROLOGY. 



while at Esquimault, in British Columbia, as we again approach 

 the ocean on the West, the Barometer comes down again nearer the 

 Nova Scotia means, although that station is 2 degrees farther North 

 than any point in Nova Scotia where the observations are recorded. 

 This comparatively small Pressure helps our climate to produce 

 agricultural results, belonging to a more southern latitude inland, 

 shewing that the atmosphere is lighter, because warmer. The 

 equability of this Pressure is also our safeguard against the violent 

 storms, which to the South, the West, the North, and East of us, 

 rage frequently, but seldom touch this Province, its extreme limits 

 being the most exposed to their ravages. This again, is partly due 

 to the level surface of Nova Scotia ; and when we complain of the 

 monotony of our low sea coast, and the want of abrupt hills through 

 the country, we should remember the compensation gained by our 

 comparative immunity from high winds and heavy rains. The 

 warmer (and lighter) air over the Gulf Stream to the Southward, 

 and the mild waters of the Bay of Fundy to the North and West, 

 assist in keeping level our Barometers, and thus preserving the 

 general regularity of our climate. 



Before leaving this topic of whole pressure, I will allude briefly 

 to a much neglected item in calculating the weight of the atmos- 

 phere. The pressure, or elastic force of vapour, must be elimin- 

 ated from the total, before we can get what we really want, — the 

 dry air to be weighed by itself. This vapour, with relative 

 humidity, is calculated from tables carefully prepared from the 

 reading of the wet bulb Thermometer, and the difference between it 

 and the day or true temperature of air. There is but a very slight 

 discrepancy between Glaisher's tables for this purpose and Guyot's , 

 but the latter is preferred, and is computed from the third edition 

 of Regnault's tensions, in which he has "modified the numerical 

 values of some of the coefficients " of the formula adopted. The 

 barometric height is supposed to be 29.700 inches. ''Enter the 

 tables with the difference of the two thermometers, and the tem- 

 perature of the wet-bulb given by observation. In the column 

 headed by the observed difference of the thermometers, and on the 

 horizontal line headed by the observed temperature of the wet 





