PORPHYRITES.                              263
	are peacocks and rams. On the ends stand boys holding up bunches of grapes in allusion to Christ's words, " I am the vine, ye are the branches." On account of these sculptures it was known during the Middle Ages as " La Tomba di Bacco," and remained uninjured on its original site within the sepulchral chapel of Sta. Costanza, until transferred by Pius VII. to the Vatican. A copy in plaster occupies its ancient niche in the Mausoleum. And to close the list, with the most important examples furnished by modern times of the application of this costly materia; to the honours of the sepulchre, the tomb wherein rests the Duke of Wellington beneath the cupola of St. Paul's is hewn out of one block of green Porphyry. The stone had been prepared by nature for the purpose, at the beginning of Time, in the shape of a boulder upon a Cornish moor Though perfectly devoid of ornament, the labour of two entire years was required to reduce it to its pattern, in situ. The Sarcophagus of Napoleon I., deposited in the sepulchral chapel under the dome of the Invalides, is carved with a grandiose simplicity of design from a single block of a red stone, not a true Porphyry but a Quartz-gritstone, of even harder texture. The rock was brought from the quarry a! Schorkisena, near St. Petersburgh, and cost, by the time it reached its destination, no less than the equivalent to 5500Z. The lid, also formed of one piece, is said to weigh 32 tons (?). Within lies the imperial corpse occupying its original tin coffin, which is again enclosed in one of mahogany, two of hard lead, and lastly in the sumptuous case of ebony made for the occasion of the funereal pro­cession on December 15th, 1840. Small pieces of Porphyry, selected for their peculiarly bright colour, were occasionally engraved upon by the later Romans, but merely as talismanic intagli, and similar devices making no pretensions to art. The ingenuity of