"Think," was Milton's answer, "of all the rivers that, for how many _millions_ of years no man can tell, have been running into the sea, and yet the sea is not overflowing." "I don't see the application of that to this underground world, don't see how all the water--there must be more streams than this one--can possibly return as vapor to the region above." "I admit," Rhodes said, "that the problem is a formidable one and that, with our present paucity of data, we can not hope to solve it. Still I think that my suggestion is sound." "But where are the openings to permit the escape of so enormous, for enormous it must be, amount of water-vapor?" "There may be countless vents, fissures, Bill, ways of egress that man will never know. Whatever the explanation, there can be no doubt that the water is going down and that this subterranean world into which we have found our way is not full." "But where does it go? Down to some sunless sea perhaps, though, if that hypothesis of yours is a sound one, bathed in light, a light never seen, in that world we have left, on land or sea." Rhodes was silent for a moment, leaning on his alpenstock. Then: "It is strange truly, the descent of the waters. And yet it would not, I believe, have been to you so very strange a thing had you known that the sea itself flows into the earth." "The sea itself?" Rhodes nodded. "Surely, Milton--why, the thing sounds like something from Jules Verne or from Lucian's _Icaromenippus_." "On the contrary," he told me, "it is not a bit out of romance either modern or ancient, but it is a fact that has long been known. At Argostoli in the Island of Cephalonia, the sea flows right into the limestone rock."[7] [Footnote 7: "The cases are certainly not numerous where marine currents are known to pour continuously into cavities beneath the surface of the earth, but there is at least one well-authenticated instance of this sort--that of the mill streams at Argostoli in the island of Cephalonia. It has been long observed that the sea water flowed into several rifts and cavities in the limestone rocks of the coast, but the phenomenon has excited little attention until very recently. In 1833, three of the entrances were closed, and a regular channel, sixteen feet long and three feet wide, with a fall of three feet, was cut into the mouth of a larger cavity. The sea water flowed into this canal, and could be followed eighteen or twenty feet beyond its inner terminus, when it disappeared in holes and clefts in the rock."--George P. Marsh: _Man and Nature_.] "Shades of Lemuel Gulliver, but this old ball that men call the earth is certainly, after all, a strange old sphere!" "How strange," said Milton Rhodes, "no scientist has ever dreamed, though your scientist has thought of things far stranger than any that were ever conceived by your wildest romancer, who, after all, Bill, is a pretty tame homo."