THE RIVER WANDLE. 35 



engineering mistake to embarrass the irrigation system with this great 

 volume of water, which ought naturally to flow to the river. 



We made a survey of the course of the river. In the Brighton 

 high-road, houses which would usually have been selected from 

 their dry situation by rheumatic gentlemen, had one or two feet of 

 clear bright water in their parlours, and their gardens were converted 

 into ponds. Proceeding up the Caterham valley, it was entirely 

 changed in character, being converted into a series of lakes. As an 

 unintentional caricature, notice boards appeared in the water itself, 

 announcing that " this eligible land " was to be let for building, and 

 scaffold boards of commencing houses appeared. This water was ex- 

 isting as large ponds in situations where at this moment no water can 

 be found within a hundred or more feet of the surface. Following 

 the course of the Bourne, we at length came to a field where the water 

 oozed out of the grass, and this was literally the top of the river. 



From our investigations it appeared to us that the Bourne arose 

 from a supersaturation of the chalk strata to a level much higher 

 than ordinary. The porous chalk acted as a sponge, and gave out 

 its water when over-saturated. It is a well-known fact that the 

 Bourne always rises when the rainfall exceeds a certain quantity 

 in a given time. Other theories have been started, such as under- 

 ground caverns or syphons ; but they are mere fanciful creations, and 

 are not required for the explanation of the phenomena. 



Near Brighton, at Patcham, a similar river to the Bourne 

 occasionally rises, which runs down the London road by Preston, and 

 empties itself into the sea near the Chain Pier. This river assumed in 

 the autumn of 1852 very considerable dimensions. I am informed that 

 another similar intermittent river runs down the Lewes Road ; but this 

 I have not myself seen. 



When the Bourne rises, it is usually followed by pestilence at 

 Croydon. In 1852 a serious epidemic of fever occurred, possibly from 

 an interference with the ordinary water-level, and disturbance of the 

 level of the cesspools which abounded before the Board of Health 

 commenced their works. 



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