GROTTO; or GROTTA, a large deep cavern or den in a mountain or rock. The word is Italian, grotta, formed, according to Ménage, from the Latin crypta. Ducange observes, that grotta was used in the same sense in the corrupt Latin. The ancient anchorites retired into dens and grottoes, to apply themselves the more attentively to meditation.
Amongst the natural caverns or grottoes of England, Okey-hole, Eldon-hole, Peak's-hole, and Pool's-hole, are famous.
The entrance to Okey-hole, on the south side of the Mendip Hills, is in the fall of those hills, is beset all round with rocks, and has near it a precipitous descent of near twelve fathoms deep, at the bottom of which there continually issues from the rocks a considerable current of water. The naked rocks above the entrance show themselves about thirty fathoms high, and the whole ascent of the hill above is about a mile, and very steep. On entering this vault, you proceed at first upon a level, but advancing farther, the way becomes rocky and uneven, sometimes ascending and sometimes descending. The roof of this cavern, in the highest parts, is about eight fathoms from the ground, but in many places it is so low that a man must stoop to get along. The breadth is not less various than the height, for in some places it is five or six fathoms wide, and in others not more than one or two. It extends in length about two hundred yards. People talk much of certain stones in it, resembling men and women, and other things; but there is little that is curious in these, which are only shapeless lumps of common spar. At the farthest part of the cavern there is a good stream of water, large enough to drive a mill, which passes all along one side, and at length glides down about six or eight fathoms amongst the rocks, and then pressing through their clefts, discharges itself into the valley. The river within the cavern is well stored with eels, and has in it some trouts; which can scarcely have come from without, as there is a considerable fall near the entrance. In dry summers, a great number of frogs are seen all along this cavern, even to the farthest part of it; and on the roof of it, at certain places, hang vast numbers of bats. The cattle that feed in the pastures through which this river runs have been known to die suddenly sometimes after a flood; which is probably owing to the waters having been impregnated, either naturally or accidentally, with lead ore.
Eldon-hole is a huge profound perpendicular chasm, three miles from Buxton, and ranked amongst the natural wonders of the Peak. Its depth is unknown. Cotton tells us he sounded 884 yards, yet the plummet still drew. But he might easily be deceived, unless his plummet was very heavy; for the weight of a rope of that length might render the landing of the plummet scarcely perceptible.
Peak's-hole and Pool's-hole are two very remarkable horizontal caverns under mountains; the one situated near Castleton, and the other close by Buxton. They seem to have owed their origin to the springs which flow through them; for when the water had forced its way through the horizontal fissures of the strata, and had carried the loose earth away with it, the loose stones would of course fall down; but where the strata had few or no fissures, they remained entire, and thus formed those very irregular arches, which are now so much admired for their grotesque appearance. The water which passes through Pool's-hole is impregnated with particles of limestone, and has incrusted the whole cavern in such a manner that it appears as one solid rock.
Grotto del Cani, a little cavern near Pozzuoli, four leagues from Naples, the air of which is of a mephitical or noxious quality; whence it is called bocca venenosa, the poisonous mouth.
Grotto del Serpi, is a subterranean cavern near the village of Sassa, eight miles from the city of Bracciano in Italy.
Milky Grotto, Crypta Lactea, a mile distant from the ancient village of Bethlehem, is said to have been thus denominated on occasion of the blessed Virgin letting fall some drops of milk whilst suckling Jesus in this grotto; and hence it has been commonly supposed that the earth of this cavern has the virtue of restoring milk to women who have grown dry, and even of curing fevers.
Grotto is also used to signify a little artificial edifice made in a garden, in imitation of a natural grotto. The exterior of these grottoes is usually adorned with rustic architecture, and the interior with shell-work, fossils, and the like, finished likewise with jets d'eau or fountains.