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Transactions. 



records of twenty months. The records give a fairly accurate tracing of 

 the movements of the water-level, but owing to a lag in rise and fall of about 

 \ in. the curve is slightly flattened. The error in timing sometimes amounts 

 to three hours. The records show three distinct classes of fluctuation- — a 

 daily fall and rise, a rise with rain, and erratic fluctuations without recog- 

 nized causes. 



The Daily Fluctuation. — Except when rain interferes, the well traces a 

 daily curve of fairly constant form with a maximum height between 6 a.m. 



Fig. 1. — Three typical weeks. 



and 9 a.m., and the lowest point at about 4 p.m. Fig. 1 shows three typical 

 weeks with the daily curves well marked. The daily curve is gradually 

 modified day by day, and the amount of fall varies between \ in. and \\ in. 

 At times " flat days," of which an example is given, appear in a series of 

 well-marked curves. No marked difTerenee between Sundays and week- 

 days has been detected. The modifications of the daily curve do not appear 



Fig. 2. —Rise and fail a r ter rain. 



to be seasonable, though the boldest curves usually appear in spring and 

 autumn. Displacement of the time at which the daily fall commences is 

 apparently associated with rain. While the causes of the daily tide are 

 still obscure, the writer believes it to be a natural phenomenon, and not 

 due to human interference with the water system. 



