TKANSACTIONS OF SECTION E. 771 



and 25 feet high, has been explored for 55 yards, but has i)Ot been surveyed. The 

 downstream cave is from 10 to 25 feet high and 30 feet wide ; it is 104 yards 

 long and ends in a pool within about 20 feet of the upper end of Marble Arch 

 Cave. The roof seems too low to admit of passage. The Marble Arch Cave is 

 entered from lower down the hillside. At the upper end of the stream course is 

 a pool, probably the continuation of the one met with in Cradle Hole. Tlie stream 

 flows for 123 yards along the ' Grand Gallery,' through boulders and shingle, to 

 the ' Junction.' The ' Grand Gallery ' is from 6 to 20 feet high and about 15 feet 

 wide. At the Junction the roof is at least 50 feet high ; from here the stream 

 turns to the left and then to the right, filling the whole of the passage ; it here 

 forms a lake at least 10 feet deep in the centre. At 81 yards from the Junction 

 a beach is reached and 10 yards further the open air, at the floor of a wide pot- 

 hole 60 feet deep ; from this beach the stream flows under low arches to another 

 lake, from which it emerges into the open just above the Marble Arch itself. 

 A high-level passage leads from above the beach to the shore of this lake, and 

 a second branch leads through boulders to the open at the bottom of a wide pot- 

 hole 30 feet deep, in the floor of which is also another opening, which will be 

 referred to later. 



From the Junction a dry passage runs to the right, and at a distance of 

 45 yards becomes 20 yards wide and about 40 feet high; the floor rises to the 

 left, but the passage continues forward to the right. To the left the rising floor 

 is composed of boulders and sand cemented together and covered with stalagmite. 

 At the upper end of the slope is a fine collection of stalactites. A low passage 

 15 feet wide leads from here into a fissure cave 30 feet high and 50 feet long. 

 The low-level passage at the bottom of the boulder slope continues for 93 yards, 

 15 to 25 feet in height and about 10 feet in width, to the ' Pool Chamber,' This 

 is about 15 yards in diameter and 20 feet high, and has a still pool at its lowest 

 point. Beyond this chamber the passage continues 15 feet wide and about 4 feet 

 high, and in 12 yards is blocked with boulders. A climb of about 15 feet vertically 

 upwards through these boulders leads into the bottom of a chamber about 80 feet 

 high and 25 yards in diameter, the floor of which is entirely composed of a slope 

 of large boulders. The upper end of the boulder slope leads to the bottom of a 

 narrow pot-hole 30 feet deep, for the descent of which ladders are necessary. At 

 the far corner of this chamber there is a small hole leading, between jambed 

 boulders, into the floor of the pot-hole into which the high-level passage opens, 

 and within 20 feet of the end of the passage. The portion of the cave beyond 

 the Pool Chamber and the two openings there were unknown before this year. 

 Fluorescine put into the Monastir Sink at 11.30 a.m. in dry weather was clearly 

 visible at Cradle Hole at 10.45 a.m. the following day, and at 6,45 the same 

 evening began to emerge at the Marble Arch spring. 



5, Mitchelstown Cave. By Dr. C. A. Hill, M.A., M.B. 



Mitchelstown Cave, the largest yet discovered in the British Isles, is situated in 

 CO. Tipperary, in the valley of the Blackwater. There are actually two separate 

 and distinct caves. The existence of one, the ' old ' cave, is now forgotten, though 

 this cave was known and exhibited in 1777. The ' new' cave, first discovered in 

 1833, is now the only one shown to visitors. It was first described by Dr. Apjohn 

 of Dublin, who partially explored and surveyed it in 1834, and published a map 

 which has been the basis of all others up to the present time. It was further 

 explored by M. Martel of Paris in 1895 and described by him, and was also 

 visited by Dr. Lyster Jameson of Dublin, who described the cave fauna found 

 therein. Very little is known of the full extent of the caves even at the present 

 day, and no reliable plan or map exists. The cave was visited in 1905 by the 

 author, who took many photographs now shown for the first time, and also 

 explored portions hitherto unvisited. The cave was found to be of much greater 

 pxtent and complexity than was previously imagined. 



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