Ingleborough forms a centre from which the rainfall on every side finds its way into the dales, through a system of caves more or less complicated, which during the last forty years have been thoroughly explored by Mr. Farrer, Mr. Birkbeck, and Mr. Metcalfe. On the south it collects in a ravine, and then leaps into a deep bottle-shaped hole called “Gaping Gill,” into which Mr. Birkbeck unsuccessfully attempted to descend, the sharp edges of the rock cutting the rope, and very nearly causing a serious accident. In depth it is about three hundred feet. The stream thence finds its way through a series of chambers and passages until it reappears in the famous Ingleborough cave, that was explored by Mr. Farrer in the year 1837, and proved to pass into the rock between seven and eight hundred yards. The present entrance of the Ingleborough cave[29] is dry, except after heavy rains, when the current reverts to its old passage. The following admirable account of the interior is given by Professor Phillips:--[30] “From Mr. Farrer’s plan and description, as given in the ‘Proceedings of the Geological Society,’ June 14, 1848, and from information obligingly communicated to me, a clear notion of the history of this most instructive spar grotto may be formed. For about eighty yards from the entrance the cave has been known immemorially. At this point Josiah Harrison, a gardener in Mr. Farrer’s service, broke through a stalagmitical barrier which the water had formed, and obtained access to a series of expanded cavities and contracted passages, stretching first to the N., then to the N.W.; afterwards to the N. and N.E., and finally to the E., till after two years spent in the interesting toil of discovery, at a distance of 702 yards from the mouth, the explorers rested from their labours in a large and lofty irregular grotto, in which they heard the sound of water falling in a still more advanced subterranean recess. It has been ascertained, at no inconsiderable personal risk, that this water falls into a deep pool or linn at a lower level, beyond which further progress appears to be impracticable. In fact Mr. Farrer explored this dark lake by swimming--a candle in his cap and a rope round his body.