METEOROLOGICAL JOURNAL. 197 



GENERAL OBSERVATIONS. 



January. — It has been ascertained, from an average of twenty- 

 seven years, that the mean depth of rain which falls at Chiswick 

 is at the rate of twenty-four inches per annum or a small fraction 

 more, the exact average being 24"024 inches. In the ten years 

 from 1826 to 1835 inclusive, the average was 24"01 inches ; and 

 in the ten years from 1830 to 1845, the average was 24"07 

 inches. But the amount in the six years from 1840 to the end 

 of 1851 was deficient to the extent of nine inches. One of these 

 years, 1848, was rather a wet season, but three consecutive years, 

 immediately preceding the present, were short of the average 

 about ten inches. The consequence was, that although at this 

 season the surface was moist, yet the lower roots of almost every 

 tree were in compact dry loam. _ The amount of rain in this 

 month was about an inch above the average. The temperature 

 was also higher than usual, especially during the day ; the nights 

 only maintained the average temperature. The wind was chieliy 

 from south-west, and was frequently boisterous, particularly on 

 the nights of the 3rd, 8th, and 21st. 



February. — The mean temperature of this month was about 

 a degree below that of the preceding, and a little more than 

 half a degree below the mean of February. This was owing to 

 the nights being generally frosty ; for the days were not colder 

 than usual. The first eight days were even mild for the period 

 of the season. The depth of rain was fully half an inch below the 

 average. North-west and south-west winds were most prevalent. 

 There was a little snow on the 10th, but scarcely so much as to 

 whiten the surface of the ground. The 8th, ITth, and 18th were 

 boisterous. 



March. — This was a very dry month, with a daily temperature 

 nearly equal to the average, but the nights were cold, the mean 

 minimum being upwards of 5° colder than usual. The nights of 

 February were colder than those of January ; and those of the 

 present month were still colder than those of February ; so that 

 as the season advanced the cold at night increased. There was a 

 sudden rise of temperature during the day between the 20th 

 and 24th ; but the nights continued frosty. The wind was nine- 

 teen days from the north-east, and five from east; and always 

 accompanied with frost at night when the sky was clear. 



April. — The weather in this month proved highly injurious to 



