One more cave I must tell you of, to show you how old some caves must be, and then I must stop; and that is the cave of Caripe, in Venezuela, which is the most northerly part of South America.  There, in the face of a limestone cliff, crested with enormous flowering trees, and festooned with those lovely creepers of which you have seen a few small ones in hothouses, there opens an arch as big as the west front of Winchester Cathedral, and runs straight in like a cathedral nave for more than 1400 feet.  Out of it runs a stream; and along the banks of that stream, as far as the sunlight strikes in, grow wild bananas, and palms, and lords and ladies (as you call them), which are not, like ours, one foot, but many feet high.  Beyond that the cave goes on, with subterranean streams, cascades, and halls, no man yet knows how far.  A friend of mine last year went in farther, I believe, than any one yet has gone; but, instead of taking Indian torches made of bark and resin, or even torches made of Spanish wax, such as a brave bishop of those parts used once when he went in farther than any one before him, he took with him some of that beautiful magnesium light which you have seen often here at home.  And in one place, when he lighted up the magnesium, he found himself in a hall full 300 feet high—­higher far, that is, than the dome of St. Paul’s—­and a very solemn thought it was to him, he said, that he had seen what no other human being ever had seen; and that no ray of light had ever struck on that stupendous roof in all the ages since the making of the world.  But if he found out something which he did not expect, he was disappointed in something which he did expect.  For the Indians warned him of a hole in the floor which (they told him) was an unfathomable abyss.  And lo and behold, when he turned the magnesium light upon it, the said abyss was just about eight feet deep.  But it is no wonder that the poor Indians with their little smoky torches should make such mistakes; no wonder, too, that they should be afraid to enter far into those gloomy vaults; that they should believe that the souls of their ancestors live in that dark cave; and that they should say that when they die they will go to the Guacharos, as they call the birds that fly with doleful screams out of the cave to feed at night, and in again at daylight, to roost and sleep.

Now, it is these very Guacharo birds which are to me the most wonderful part of the story.  The Indians kill and eat them for their fat, although they believe they have to do with evil spirits.  But scientific men who have studied these birds will tell you that they are more wonderful than if all the Indians’ fancies about them were true.  They are great birds, more than three feet across the wings, somewhat like owls, somewhat like cuckoos, somewhat like goatsuckers; but, on the whole, unlike anything in the world but themselves; and instead of feeding on moths or mice, they feed upon hard dry fruits, which they pick off the trees after the set of sun.  And wise men will tell you, that in making such a bird as that, and giving it that peculiar way of life, and settling it in that cavern, and a few more caverns in that part of the world, and therefore in making the caverns ready for them to live in, Madam How must have taken ages and ages, more than you can imagine or count.