Further down Total Depravity Passage we were not urged to go, because at that season of the year it is wet and difficult, without any sufficient promise of a brilliant compensation for the achievement of such a journey. But the Spring of Youth Room, or as it is generally called, the Spring Room, is more than ample justification for the existence of the passage, and would still be if that passage were several miles in length and the attraction located at the most distant limit. [Illustration: Wall in Spring Room. Page 32.] The various passages in Marble Cave are by no means alike or even similar; some having been opened by the action of water assisted only by acid carried in solution; while others are the unmistakable crevices of earthquake origin, afterwards enlarged, or perhaps only remodeled, as we might say, by the water's untiring energy in changing the position of rock masses without obliterating evidences of original design. A glance at the map shows the sudden breaking off of the various passages represented; the end, however, is not of the passages themselves, but only of the exploration or the survey of them, and there is a possibility that future developments will lead to the discovery of more caves than are yet known. However that may be, the glimpses already had into the beyond are said to be alluring. To the north of the Auditorium, which was until recently called the Grand Amphitheater, there opens out a kind of alcove extension known as the Mother Hubbard Room, and spreading out from this is the corridor, a room about one hundred and twenty-five feet long and seventy-five feet in width, with a low, narrow passage, or crawl, leading from the northeast into the Grotto, a dome-shaped room formerly called the Battery, on account of the great number of bats that used to congregate in it. It is about forty feet in diameter and fifty feet in height. On one side of this room is a narrow "squeeze" opening into a passage several feet lower than the floor level of the Grotto and leading to the Spanish Room, which when discovered bore indications of having been occupied by a human being who had tried to escape by tunneling, or by reaching a hole in the roof; which is said to be impossible for him to have done without outside assistance. As no bones have been found we may hope the assistance arrived in time. When the discovery of the room was made, a quantity of loose rock was piled before the entrance, so if he ever escaped it was not by that way.