METEOROLOGICAL OBSERVATIONS AT CHISWICK IN 1903. 551 



February was the most unseasonably warm and dry month, and June 

 the most unseasonably cold and wet one. As affecting vegetation the 

 most noteworthy features were the keen frosts of April, coming as they 

 did after a warm and forward March ; the three weeks of warm and 

 very dry weather between midsummer and the middle of July ; and the 

 continuous and heavy rainfall in October. 



Diagram 2. — The average April day is about 6 degrees warmer than 

 an average day in March, while the nights are as a rule about 3 degrees 

 warmer in the former month than in the latter. But in 1903 this order was 

 reversed, for the April days were a degree colder and the nights 2 degrees 

 colder than those in March (fig. 161). This will be seen in the sudden dip 

 downwards of the two curves between March and April in the otherwise 

 fairly regular advance in temperature between January and July. It 

 will also be noticed that, whereas the days in June were 4 degrees colder 

 than is seasonable, the nights were less than 3 degrees colder than the 

 average. Then again in October, while the days were only 3 degrees 

 warmer, the nights were as much as 5 degrees warmer than is seasonable. 



Diagram 3. — The fall in the mean temperature of the air between 

 March and April is very marked (fig. 162), but in the ground-temperature 

 curves there is no such dip, although a certain deflection from the normal 

 is evident in the case of the temperature curve for one foot deep. This 

 is no doubt owing to the fact that the cold weather in April only set in 

 shortly before the middle of that month, and there were several warm 

 days at its close, so that there was not sufficient time for the temperatures 

 at the other depths to be seriously affected. In the coldest month, 

 December, the soil at four feet deep was, on an average, 8 degrees warmer 

 than the air ; at two feet deep 5 degrees warmer, and at one foot deep 

 2 degrees warmer than the air. In the warmest month, July, the soil at 

 four feet deep was 4 degrees colder than the air, at two feet deep it was 

 of nearly the same temperature as the air, but at one foot deep the soil was 

 2 degrees warmer than the air. 



