XCVi Proceedings, 



generally met with a cordial and ready response. There are 

 still, however, portions of our district where a few more rain- 

 gauges would be acceptable ; for instance, the crest of the 

 North Downs and the vicinity of Erith. Nevertheless, having 

 some acquaintance with the statistics of rainfall, I have no 

 hesitation in expressing my behef that there is no area of equal 

 extent to the Croydon district in any other part of the country 

 over which the rainfall is better observed. At the end of the 

 year the number of stations had reached 48, being at the rate 

 of one gauge to about every ten square miles. This is probably 

 sufficient. The efforts of the Club may now, I think, be directed 

 to the more uniform distribution of the gauges. The Club is 

 much indebted to the Photographic Subsection for photographs 

 of several of the stations, which will be preserved as permanent 

 records of the surroundings of the gauges. The Eeport of the 

 Meteorological Sub-Committee for the year 1888 will be found 

 in the Transactions (Trans., Art. 73). 



While the depth of rain falling on the surface of the earth is 

 thus noted, the movements of the water below, being that 

 portion of the rain which escapes evaporation, has not been 

 neglected. This subject of research has been termed " hydro- 

 geology," and is pursued mainly by observing the height of the 

 water in wells. Before now considerable misconception has 

 arisen concerning the hydrogeology of this district, through the 

 levels of the water not having been referred to the same epoch. 

 But the inquiry has been pursued with success for several years 

 by our member, Mr. Latham, who has been thereby able to 

 predict some time in advance, in rainy seasons, the outburst of 

 the bourns in the Caterham Valley. Last year I referred to the 

 well-gaugings undertaken by the Croydon Corporation. It baa 

 been thought advisable to defer their publication till they could 

 appear in conjunction with the rainfall tables. They are now, 

 thanks to the kindness of our member, Mr. Walker, the Borough 

 Engineer, completed to the end of the year 1888. They do not, 

 it is true, exhibit continuous records of the height of the water 

 in the wells, as would be shown by self-recording gauges ; but 

 they do show the connection between the rainfall and the move- 

 ments of the subterranean water. From these gaugings it is 

 manifest that the rainfall in autumn and in winter is more 

 efficacious in replenishing the wells than an equal amount of 

 rain in a similar interval of time in the spring or summer, 

 when a larger proportion of the rain is withdrawn from the soU 

 and restored to the atmosphere by evaporation. But these great 

 operations of Nature are slow in their processes, and the effects 

 are not immediately manifest. As a consequence, on the 

 average of years, it is not till November that the water in the 

 wells in the hig;her part of the district begins to rise from its 



