50 NATURE NEAR LONDON. 



sheer wanton mischief is undoubtedly the cause in 

 some cases, and it has been suggested that quicksilver 

 has occasionally been inserted in gimlet holes. The 

 mercury is supposed to work up the channels of the 

 sap, and to prevent its flow. 



But may not the ordinary conditions of suburban 

 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 

 Bome 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 fre- 

 quently leak, so much so that the soil for yards is 

 saturated and emits a smell of gas. Eoots passing 

 through such a soil can scarcely be healthy, and 

 very probably in making excavations 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 prominent 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 

 defined, and which blotted out distant objects and 

 blurred those nearer at hand. The appearance of the 

 open arable field over which I was looking changed 

 as it approached. 



