GROTTO, a large deep cavern or den in a mountain or rock.
Of these we find several remarkable ones in different parts of the world. The most celebrated one of our own country, is that called Oakley-hole, on the
south side of Mendip hills. Its length is about two hundred yards, and its height various; being in some places very low, and in others eight fathoms. There is another at Puzzoli, about four leagues from Naples, called the Dog's Grotto; because a dog thrown into it is immediately killed, by a destructive vapour equally fatal to all animals within its reach. The milky grotto, crypta lactea, about a mile from the ancient village of Bethlehem, is said to have been thus called from the holy virgin's letting fall some drops of her milk in it; on which account the earth of this cavern has been supposed to possess the virtue of restoring women's milk.