the water, the ancients appear to have used in very early times a species of pounded sea-shells, introduced carefully into the seams and chinks between the planks—a process found to answer well for a short time; when, however, the ship strained, this caulking was liable to fall out, letting in the water as before. A somewhat similar method is described in the Transactions of the Embassy sent to China in 1792, as seen there at that time.
In later days, other methods were adopted; one of which, attributed by Pliny to the Belgæ,[1] consisted in beating pounded seeds into the fissures between the planks of vessels—a substance, he says, found to be more tenacious than glue, and more to be relied on than pitch. This is evidently the same in principle as the modern practice of caulking. In the same way we find in remote times that pitch and wax were used partly for the prevention of leakage, and partly also to preserve the planks from the sea-weeds and animalculæ with which the waters of the Mediterranean abound.[2] The discovery, too, of what is supposed to have been a galley of Trajan at the bottom of Lake Riccio shows clearly that, in Roman times, sheathing as well as caulking were used to preserve the bottoms of ships. The famous Locke,[3] alluding to this discovery, says, "Here we have caulking and sheathing together above sixteen hundred years ago; for I suppose no one can doubt that the sheet of
