On the left of Silliman’s Avenue is a hall with fine acoustic properties, thirty feet wide, forty long, and twenty high, where the famous Norwegian violinist Ole Bull is said to have once given a special performance; and hence it bears his name, Ole Bull’s Concert Hall. The wild and rugged pass which, on the map, seems to be a continuance of Silliman’s Avenue, is really on a lower level, and is well named “El Ghor” (The Gorge). It winds about like a forsaken river bed, which it undoubtedly is, and offers many surprising sights. One such is the Fly Chamber, in which swarms of house-flies seem to have settled on the walls and ceiling. Examination proves them to be so many crystals of black oxide of manganese. The Hanging Rocks, the Sheep-shelter, and the Victoria Crown are formations whose names suggest their shape. Immediately over El Ghor is Corinne’s Dome, nine feet wide and about forty feet high. The guide points out what he styles Suicide Rock, and when you innocently ask him “Why?” his ready reply is, “Because it hung itself.” The Black Hole of Calcutta is an ugly black pit on the left of the pass. El Ghor continues on for some distance, but we leave it after refreshing ourselves at Hebe’s Spring, a clear pool four feet in diameter by a foot and a half deep, and said to be impregnated with sulphur; a fact of interest—it might easily come from the reduction of gypsum or Epsom salt. Stevenson, who was here in 1861, says, “There is a short avenue, or rather a hole, leading from El Ghor to a sheet of water called Mystic River, which has not been explored, as they have never been able to get a boat in there.” Other early writers mention Mystic River, but Dr. Call and myself were unable to find it. Possibly it is identical with the stream in Martel Avenue; but no one would ever think of a “boat” in connection with the latter. Boone Avenue, diverging from El Ghor to our left at a point five thousand eight hundred and twenty yards from the mouth of the Cave, was for many years blocked by a stone stairway, recently removed. Important discoveries were made in this direction in 1907, to which we shall presently give attention. Now, however, we climb up through an uninviting hole at our right that admits us to an upper tier of caverns. When the last man is through we burn blue fire, and are surprised to find ourselves in a stone vineyard. Nodules and globules simulate clusters on clusters of luscious grapes, gleaming with parti-colored tints through dripping dew. No covetous hand is allowed to pluck the marvelous vintage of Mary’s Vineyard; which, after all, the mineralogist explains as simply calcium carbonate coated with the black oxide of iron.