98 MEAN METEOROLOGICAL RESULTS 



and December, the monthly means were relatively high. The depres- 

 sion (3°.9) in the temperature of May, was never exceeded in any May 

 of former years, and was nearly approached only ia 1849 and 1851, 

 when in both cases the cold of May was succeeded bj^ unusual warmth 

 in June and July. The abnormal warmth of April served only to 

 aggravate the evil, by hastening the vegetation that was thrown back 

 by the frosts that followed in May. The bad effects of a generally 

 low summer temperature may perhaps be modified, as regards some 

 plants, by occasional bursts of heat, though they be necessarily ba- 

 lanced by unusually low temperatures at other parts of the season. 

 No such mitigating circumstances occurred in 1861, as the warmest 

 day and the absolutely highest temperature of the year were both 

 considerably below the twenty-two years' average of these quan- 

 tities. 



The hygrometric condition of the summer was not favourable ; the 

 mean relative humidity of May, June, and July, being 70 against 74» 

 the twenty-one years' average for these months. But as the tempera- 

 tures were low, the foregoing numbers do not present so strong a con- 

 trast as do the tensions of vapour, which for the same three months 

 were "359 in 1861, and '393 on the average of twenty-one years. The 

 contrast in this respect between 1860 and 1861, was very conspicuous 

 in May, the tension of vapour for this month being more than 41 per 

 cent, greater in 1860 than in 1861. 



May and June were 8 per cent, and 16 per cent, less cloudy than is 

 usual in those months ; while later in the season, when a bright sun 

 is more in request, clouds were more than 20 per cent, in excess. 



The depth of rain, which on the whole year was three inches in 

 defect was deficient in June and July to the extent of more than an 

 inch and a half. In May, when rain is an hindrance to gardening 

 and agricultural operations, it was rather in excess ; while, as before 

 stated, there was a want of that moisture in the air whose presence is 

 favourable to the development of young leaves. 



In the following summary, the chief meteorological elements rela- 

 tive to the year 1861, are compared with the average results derived 

 from a series of years, as well as with extreme values that have oc- 

 curred durina; the same series : 



