124 



E. F. PITTMAN. 



bores visited by him. The characteristic odour however 

 is distinctly noticeable at most of the bores, and the occur- 

 rence of sulphuretted hydrogen is doubtless due to the 

 reducing action of decomposing organic matter upon sul- 

 phates, the latter being probably derived from the oxidation 

 of pyrites, which usually occurs in the vicinity of intrusive 

 dykes. 



Tidal Wells.— While no satisfactory explanation can as 

 yet be offered to account for the rise and fall of the water 

 in the Urisino Well (N.S. Wales), the suggestion made by 

 Gregory, 1 that the phenomenon may be due to the escape 

 of carbonic acid gas, cannot be endorsed. There is no 

 visible evolution of gas, the surface of the water being 

 apparently quiescent; moreover the writer stood for a con- 

 siderable time on a staging which had been erected inside 

 the mouth of the well, and the fact that the air there was 

 perfectly innocuous is proof that there was no accumula- 

 tion of carbon dioxide. The suggestion as to geyser action 

 would appear to be equally untenable. It may be added, 

 that the Professor is mistaken in supposing that more than 

 one tidal well is known in New South Wales. The Ninety- 

 one Mile is a Government bore, situated about six or seven 

 miles from the Urisino bore, but it does not exhibit varia- 

 tions in the height of the water as the latter does. It is 

 probable that the two names have been confused on account 

 of the Urisino being so close to the Ninety-one Mile. 



Oxtoii Downs Bore— Water in Granite?— The artesian 

 bore at Oxton Downs (Queensland) is said to have obtained 

 its supply from granite, and Professor Gregory regards this 

 as certain evidence that the ivater is plutonie. 2 If it could 

 be proved that this water was actually derived from granite 

 the occurrence would be unique, for although very many 



1 Dead Heart of Australia, p. 330. 

 8 Ibid., p. 317. 



