Hilgendorf. — Fluctuations in Water-level of Artesian Wells. 493 



a good, flow resulted. This well was completed on the 10th February, 1864, 

 and on the 15th February, 1864, the Council started another well, this time 

 in Cathedral Square. For the above information I am indebted to Mr. J. 

 Lothian Wilson, of Kaiapoi. From this date onwards for about fifty years 

 thousands of private wells were sunk in the Christchurch area, and it was 

 soon found that the earlier ones, sunk to depths of 40 ft. and 80 ft., suffered 

 a serious and continuous fall in their static level. Deeper and deeper wells 

 were then sunk, tapping various water-bearing strata down to 400 ft. in 

 depth. The fall in the static level of large numbers of wells was viewed 

 very seriously, as indicating a possible failure of the water-supply ; but the 

 evidence of Hutton and Speight's long-period observations on the Museum 

 well shows that the fall has been checked, if not arrested. The static level 

 of the 190 ft. well above Hutton's datum was, in 



1894 .. . . 9 ft. 8 in.) . , n OK . 



i Average fall per vear, 3-D in. 



1910 . . . . 5 ft, 3 in. 



1916 . . . . 5 ft. in. I Avera ^ e M] P er > Tear ' °' 5 in - 



At the time Hutton made his observations he estimated the yearly fall 

 at 5-5 in., so that its rate has been greatly reduced during the last twentv- 

 two years. 



Why the wells have ceased to fall is not certain. There are good grounds 

 for believing that it is due to natural causes connected with the supply of 

 water from the Waimakariri and the under-drainage to the sea. But in 

 1909 the City Council sank, within the area of an acre or two, four wells, 

 8 in. in diameter, to the 80 ft. stratum, and from these and three similar 

 wells sunk in 1912 water is pumped to supply nearly the whole town. From 

 this date, then, the sinking of private wells almost entirely ceased, and this 

 fact may have so important a bearing on the static level of the pre-existing 

 wells that the matter is not suitable for discussion until a new series of long- 

 period observations have been made. 



Art. XLIII. — -Note on the Fluctuation of Water-level in a Christchurch 



Artesian Well. 



By L. P. Symes. 



[Read before the Philosophical Institute of Canterbury, 2nd August. 1916 ; received by 

 Editors, 30th December, 1916 ; issued separately, 10th December, 1917.] 



Many writers, notably Hutton, Speight, and Hilgendorf, have discussed 

 the Christchurch artesian system, and have shown that the water-level 

 rises every evening, that it rises with rain, and that the Waimakariri River 

 has no apparent influence. Hutton also described a " Sunday rise." These 

 results were foimded on intermittent observations made at hourly or less 

 frequent intervals. To obtain more definite knowledge the writer, in con- 

 junction with Dr. Hilgendorf, set up an instrument to make continuous 

 records of the fluctuations in water-level. An isolated well at Papanui. 

 not in use, was selected, though unfortunately its depth is not yet ascer- 

 tained. This note deals with some of the results obtained through the 



