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being extremely thin, and not capable of supporting it-self, it soon breaks to pieces ; and in its failure sometimesinvolves even that of the wall. It is not, therefore, with-out reason that the inhabitants of Utica allow no bricksto be used in their buildings which are not at least fiveyears old, and also approved by a magistrate. There arethree sorts of bricks ; the first is that which the Greeks callDidoron (didagov'), being the sort we use ; that is, one footlong, and half a foot wide. The two other sorts are usedin Grecian buildings; one is called Pentadoron, the otherTetradoron. By the word Doron the Greeks mean apalm, because the word dwgov signifies a gift which canbe borne in the palm of the hand. That sort, therefore,which is five palms each way is called Pentadoron; thatof four palms, Tetradoron. The former of these twosorts is used in public buildings, the latter in private.Each sort has half bricks made to suit it; so that whena wall is executed, the course on one of the faces of thewall shews sides of whole bricks, the other face of halfbricks; and being worked to the line on each face, thebricks on each bed bond alternately over the coursebelow. Besides the pleasant varied appearance whichthis method gives, it affords additional strength, by themiddle of a brick, on a rising course, falling over thevertical joints of the course thereunder. The bricks ofCalentum in Spain, Marseilles in France, and Pitane inAsia, are, when wrought and dried, specifically lighterthan water, and hence swim thereon. This must arisefrom the porosity of the earth whereof they are made;the air contained in the pores, to which the water cannotpenetrate, giving them a buoyant property. Earth of