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 Ookley-hole, on the fourth 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.

GROTTO is also used for a small artificial edifice made in a garden, in imitation of a natural grotto.

The outsides of these grottos are usually adorned with rustic architecture, and their inside with shell-work, coral, &c. and also furnished with various fountains, and other ornaments.

The following is recommended as a good cement for grotto work. Take two parts of white rosin, melt it clear, add to it four parts of bees wax; when melted together, add some flower of the stone you design to cement, two or three parts, or so much as will give the cement the colour of the stone; to this add one part of the flower of sulphur: first incorporate all together over a gentle fire, and afterwards knead it with your hands in warm water. With this fasten the stones, shells, &c. after they are well dried, and warmed before the fire.