In constructing works of this kind in the water, the material used is sometimes stone and sometimes earth. So far as earth is employed, it is necessary to resort to some means to prevent its spreading under the water, or being washed away by the dash of the waves at its sides. This is usually effected by driving what are called _piles_, which are long beams of wood, pointed at the end, and driven into the earth by means of powerful engines. Alexander sent parties of men into the mountains of Lebanon, where were vast forests of cedars, which were very celebrated in ancient times, and which are often alluded to in the sacred scriptures. They cut down these trees, and brought the stems of them to the shore, where they sharpened them at one end and drove them into the sand, in order to protect the sides of their embankment. Others brought stones from the ruins and tumbled them into the sea in the direction where the pier was to be built. It was some time before the work made such progress as to attract much attention from Tyre. At length, however, when the people of the city saw it gradually increasing in size and advancing toward them, they concluded that they must engage in earnest in the work of arresting its progress.