2o8 The Irish NaHiralist. October, 1912.. 



Grasshopper-Warblers from Tuskar Light -station. 



At midnight on Monday, July 22nd, a Grasshopper -Warbler was obtained 

 by Mr. O'Leary, light-keeper, as it fluttered on the lantern glass, and on 

 Wednesday, September nth, at 10.25 p.m., I captured another as it 

 skulked on the balcony. 



C. J. Patten. 

 Tuskar, Co. Wexford. 



Avocet at Lough Swilly. 



About the middle of October, 191 1. Mr. J. Swan shot an Avocet {Recur- 

 virostra avocetta Linn.), at the mill-dam, Buncrana, Lough Swilly. The 

 bird had frequented the dam for some days along with other invaders 

 before it fell a victim to the gun. It was seen in the flesh by my friends, 

 Messrs. R. & W. Logan, and from what they have told me the identification 

 is undoubted. 



D. C. Campbell, 



Londonderry. 



GEOLOGY. 



An Old County Dublin Mine. 



Do any readers of this Journal know anything of the spot known as the 

 " mine hole," on the beach, half-way between Dalkey and Killiney ? 

 It is apparently a worked -out vein occurring at the junction of the slate 

 and the granite. I got in recently as far as its second branching, some 

 sixty-five paces from the entrance, but not being prepared to wade, did 

 not go any farther, though the water did not seem very deep. About 

 twenty-five paces from the entrance, are two passages starting from a 

 small chamber on the right, the first ends after five yards in a six-foot drop 

 into a pool of water, by the main passage one has just left, the other 

 terminates a curved course of about twenty paces in a sort of shallow 

 well. There is no mention of it in the Memoir of the Geological Survey 

 dealing with Sheet 112, though it describes this part of the beach rather 

 minutely. The beach in front of the cave is strewn with specimens of 

 the andalusite mica schist, mentioned in the Memoir. This absence of 

 mention may be due to the fact that years ago the entrance was closed 

 by an iron gate, which has disappeared. I am told the entrance at present 

 forms the abode of an old man who has lived there for some time, and 

 that other exits may be seen some distance inland. 



Perhaps it might be of sufficient interest to some geologists to explore 

 and give us an account of it. Can anyone say what is the origin of the 

 subterranean passages, lighted from above, and connected with a " holy 

 well " near the convent at Dalkey ? 



F, Hyde Maberly. 



Crosshaven, Co, Cork, 



