DEPTH OF WELLS. 



183 



perfect if we were able to refer all the wells to a common level, a task 



which is, however, almost impossible, unless the most careful levelling 



were resorted to. As the case stands, a well which is situated in a 



ravine and which is, say, 200 feet in depth is classified in that class, 



although it ought to be included in the same class with a deeper well, 



when the latter is situated on the plateau. I have, however, found 



that such a correction would not materially alter the results, and 



that for all practical purposes the classification, as suggested in my 



former papers, is quite sufficient. The classes were— 



I Class, all wells below 151 feet in depth. 



II „ wells from 151 to 200 feet in depth. 



III „ „ „ 201 to 250 „ „ „ 



IV „ „ „ 251 to 300 „ „ „ 



more than 300 



» » » 



According to this classification the following numbers of produc* 

 tive wells were registered in :-- 



Class. 



Depth. 



1888. 



1891. 



1893. 



1895. 



I . 



II . 



III . 



IV . 

 V 



Below 151 feet .... 



From 151 to 200 feet. . 



From 201 to 250 feet .... 



From 251 to 300 feet. , 



More than 300 feet • • . • 



Total 



33 



143 



35 



3 



59 



97 



187 



33 

 1 



36 



86 



187 



97 

 ... 



86 



127 



192 



105 



9 





281 



377 



406 



519 



Three features are very striking ; the large increase of the shal- 

 lower wells, namely, such of 200 feet and under since 1888, and the 

 equally large, if not larger increase of the deeper wells and the re- 

 markable constancy of the medium depth wells. 



In 1888 the shallower wells (I and II Class) aggregated 100, a 

 figure which increased considerably in 1891, but fell off again in 1893 

 when no more fresh wells were sunk, and the existing ones gradually 

 deepened. In January 1895 the shallow wells reached the unpre- 



( 229 ) 



