Grotto, is also used for a little artificial edifice made in a garden, in imitation of a natural grotto. The outsides of these grottoes are usually adorned with rustic architecture, and their inside with shell-work, fossils, &c. finished likewise with jets d'eau or fountains, &c.

A cement for artificial grottoes may be made thus: Take two parts of white rosin, melt it clear, and add to it four parts of bees wax: when melted together, add two or three parts of the powder of the stone you design to cement, or so much as will give the cement the colour of the stone: to this add one part of flower of sulphur: incorporate all together over a gentle fire, and afterwards knead them with your hands in warm water. With this cement the stones, shells, &c. after being well dried before the fire, may be cemented.

Artificial red coral branches, for the embellishment of grottoes, may be made in the following manner: Take clear rosin, dissolve it in a brass-pan; to every ounce of which add two drams of the finest vermilion: when you have stirred them well together, and have chosen your twigs and branches, peeled and dried, take a pencil and paint the branches all over whilst the composition is warm; afterwards shape them in imitation of natural coral. This done, hold the branches over a gentle coal fire, till all is smooth and even as if polished. In the same manner white coral may be prepared with white lead, and black-coral with lamp-black.

A grotto may be built with little expense, of glaas, cinders, pebbles, pieces of large flint, shells, mofs, stones, counterfeit coral, pieces of chalk, &c. all bound or cemented together with the above described cement.