It is very possible that the Jockey Cap may be the result, not of the continuous, but of the intermittent drip of water containing carbonate of lime, and that therefore the present rate of growth is not a measure of its past or future condition. Its age in 1845 was estimated by Professor Phillips at 259 years, on the supposition that all or nearly all of the carbonate of lime in each pint was deposited. If, however, it grew at its present rate, it may be not more than 100 years old; and if it be taken as a measure of the rate generally, all the stalagmites and stalactites in the cave may not date further back than the time of Edward III. It is evident, from this instance of rapid accumulation, that the value of a layer of stalagmite in measuring the antiquity of deposits below it, is comparatively little. The layers, for instance, in Kent’s Hole, which are generally believed to have demanded a considerable lapse of time, may possibly have been formed at the rate of a quarter of an inch per annum, and the human bones which lie buried under the stalagmite in the cave of Bruniquel, are not for that reason to be taken to be of vast antiquity. It may be fairly concluded, that the thickness of layers of stalagmite cannot be used as an argument in support of the remote age of the strata below. At the rate of a quarter of an inch per annum, twenty feet of stalagmite might be formed in 1,000 years. _The Descent into Helln Pot._ The subterranean passages grouped round Helln Pot, a tremendous chasm near Selside, on the east of Simon’s Fell in Ribblesdale, illustrate in a remarkable degree the mode in which the water is at present wearing away the rock. Those which have been explored constitute the Long Churn Cavern, which is comparatively easy of access through a hole known as Diccan Pot (Fig. 2, _a_). On descending into it, the visitor finds himself in the bed of a stream that now roars in a waterfall, now gurgles over the large fallen blocks from the roof, and that here and there has worn for itself deep pools by the mechanical friction of the sand and pebbles brought down by the current. If it be followed down after passing over a waterfall, the light of day is seen streaming upwards beneath the feet from the point where the water leaps into the great chasm of Helln Pot (Figs. 2, _b_. 3, _a_). Above the entrance there is a complicated network of passages, some dry, and some containing streams which have not yet been fully explored. [Illustration: FIG. 2.--Diagram of Helln Pot and the Long Churn Cavern.]