NOW to return to Tom and Becky's share in the picnic. They tripped along the murky aisles with the rest of the company, visiting the familiar wonders of the cave--wonders dubbed with rather over-descriptive names, such as "The Drawing-Room," "The Cathedral," "Aladdin's Palace," and so on. Presently the hide-and-seek frolicking began, and Tom and Becky engaged in it with zeal until the exertion began to grow a trifle wearisome; then they wandered down a sinuous avenue holding their candles aloft and reading the tangled webwork of names, dates, postoffice addresses, and mottoes with which the rocky walls had been frescoed (in candle-smoke). Still drifting along and talking, they scarcely noticed that they were now in a part of the cave whose walls were not frescoed. They smoked their own names under an overhanging shelf and moved on. Presently they came to a place where a little stream of water, trickling over a ledge and carrying a limestone sediment with it, had, in the slow-dragging ages, formed a laced and ruffled Niagara in gleaming and imperishable stone. Tom squeezed his small body behind it in order to illuminate it for Becky's gratification. He found that it curtained a sort of steep natural stairway which was enclosed between narrow walls, and at once the ambition to be a discoverer seized him.