On Artesian or Overjlowing Wells. 119 



lion should be subject to a similar disturbance. M. Hericart do 

 Thury mentions this of a well bored to the depth of 17 yards 

 at Noyelle-sur-Mer. — (Annul, de Tlndustrie^ t. ii. p. 66). At 

 time of ebb, its level is 2 yards under ground, while at flood, 

 it is on a level with it : a very ingenious valve has, therefore, 

 been constructed, to maintain the well even during ebb at the 

 higher level. Similar oscillations also occur in the Artesian 

 wells at Abbeville, besides others at Dieppe, Montreuil, Depart- 

 ment of Calvades, and the United States. 



What extensive fissures the water here and there must fill, is 

 not only demonstrated by the magnitude of many of these 

 springs, but also by a circumstance mentioned by M. Gamier, 

 on the authority of M. Hericart de Thury. In a brewery at 

 Paris, near the barrier towards Fontainbleau, a well, 20 yards 

 deep, ceased to yield any more water. They, therefore, resol- 

 ved to sink the shaft deeper. But a depth of 19 yards was 

 scarcely reached, when suddenly the borer sunk down into a 

 crevice for more than 7 yards, and would have been inevitably 

 lost, as even then it did not reach the ground, if fortunately a 

 cross bar of wood had not been passed through the eye at the 

 top of the instrument. The boring machine was tossed too and 

 fro, as if it was moved by a large body of water, and, when 

 after much difficulty, it was drawn up to the opening, the water 

 suddenly sprung 10 yards above the heads of the workmen, so 

 that they could scarcely escape quickly enough, and were oblig- 

 ed to leave all their implements in the well. Ever since, the 

 water has stood 12 yards above the circle, which serves as a 

 foundation to the wall of the well. 



This irruption of the water, on first piercing these subter- 

 ranean reservoirs, is often very violent, and is no small proof of 

 the copiousness of many of these wells. Some striking examples 

 of this are quoted from England in the Bibliotheque Univer- 

 selle, t. xxxix. p. 199- A Mr Brook had sunk a bore in his 

 garden 360 feet deep, and 45 inches in diameter, from which 

 the water was discharged so copiously, that it not only over- 

 flowed the whole yard round the house, but also submerged the 

 adjoining cellars. The damage was so great that the neighbours 

 lodged a complaint, and the police were required to interpose. 

 Two men now tried to close the bore with a wooden peg, but 

 they were constantly driven back by the violence of the water 



