of Overflowing Wells. 165 



Lastly, Besides attending to these circumstances, it is neces- 

 sary to be possessed of perseverance and courage, which will 

 lead us to disregard the delays and difficulties often unavoidably 

 connected with the operations of boring. — Hericart de Thury. 



Observations on the Snake called Yellow Tail ( Coluber Jlavi- 

 colis, Linn., belonging to the division of Cerberus of Cxxy'ier), 

 and on the supposed power of Fascination in Serpents. By 

 Dr J. Hancock, Corresponding Member of the Zoological 

 Society, and of the Society of Arts for Scotland, &c. &c. 

 (Communicated by the Author.) 



JL HAVE examined several specimens of this serpent, and the 

 following are some of the results of my observations. 



The head is rather small, oblong, angular, and pointed, and 

 has large scales ; two rows of fine teeth on each side the upper 

 jaw, and one row on each side the lower. It has 211 abdominal 



blind routine, and are apt to be discouraged, when in a different country they 

 do not see the sound bringing up the kinds of earth and stone to which they 

 have been accustomed. The levels of water, and the manner of determining 

 their rise, are often unknown to them. Sometimes by their haste to sink the 

 tubes, they prevent the sheets of water from ascending to the surface ; and they 

 are frequently discouraged, because they do not find succeeding each other 

 the formations in which they have been accustomed to see water springing. 

 Lastly, some of them having no knowledge of the art, have been seen ex- 

 posing theii' workmen, without any precaution, in the bottom of deep wells, 

 where they run the greatest risk when they approach impermeable beds 

 covering the sheets of compressed water. These waters sometimes coming 

 from distant and very elevated reservoirs, often rise at the very moment of 

 boring, in such..<iuantity and with such impetuosity, that the workmen 

 scarcely have time to ascend to the surface, and have even perished before 

 they were able to give any signal of distress. Frequently the irruption of 

 the compressed waters is accompanied with a disengagement of air, which 

 escapes with such noise and impetuosity, that the workmen are thrown over, 

 and others have compared the effect of this disengagement of air to a violent 

 blow upon the body or arms. It is this disengagement .of air which has led 

 some persons to think that the ascent or springing of the water of bored 

 wells is owing to the pressure of the atmospheric air in great subterranean ca- 

 vities. If this cause be admitted for the rising of water at the very moment 

 when the impermeable stratum is perforated, it remains to be examined why, 

 the air once disengaged, the water continues to spring, although it no longer 

 undergoes pressure Ironi the air. 



