44 NATURE NEAR LONDON 



improvement often account for the decay of such trees 

 without occult causes? Sewers carry away the water 

 that used to moisten the roots, and being at some 

 depth, they not only take the surface water of a storm 

 before it has had time to penetrate, but drain the lower 

 stratum completely. Then, gas-pipes frequently leak, so 

 much so that the soil for yards is saturated and emits a 

 smell of gas. Roots passing through such a soil can 

 scarcely be healthy, and very probably, in making ex- 

 cavations for laying pipes the roots are cut through. 

 The young trees that have been planted in some places 

 are, I notice, often bored by grubs to an extraordinary 

 extent, and will never make sound timber. 



One July day, while walking on this road, I happened 

 to look over a gateway and saw that a large and pro- 

 minent mansion on the summit of some elevated ground 

 had apparently disappeared. The day was very clear 

 and bright, sunny and hot, and there was no natural 

 vapour. But on the light north-east wind there came 

 slowly towards me a bluish-yellow mist, the edge of 

 which was clearly denned, and which blotted out distant 

 objects and blurred those nearer at hand. The appear- 

 ance of the open arable field over which I was looking 

 changed as it approached. 



In front of the wall of mist the sunshine lit the field 

 up brightly, behind the ground was dull, and yet not in 

 shadow. It came so slowly that its movement could be 

 easily watched. When it went over me there was a per- 

 ceptible coolness and a faint smell of damp smoke, and 

 immediately the road, which had been white under the 

 sunshine, took a dim, yellowish hue. The sun was not 

 shut out nor even obscured, but the rays had to pass 

 through a thicker medium. This haze was not thick 

 enough to be called fog, nor was it the summer haze 



