The Romans covered domes in lead; during the Byzantine empire they very generally did so. Constantinople in the age of Justinian was a city of lead domes, as it has always since remained. The domes of St. Sophia are still covered with lead laid over the brickwork. This tradition was carried on by the Greek master builders who erected the great mosques for the conquerors. A large mosque has as many as twenty or thirty domes of all sizes grouped about the central one. The bazaars, caravansaries, and bakeries, have long level rows of cupolas. This prospect of dome beyond dome in a succession as of billows is of marvellous beauty in a general view of the city as seen from the sea. The lead is laid over the brickwork, the rolls are very small, and as they have no wood core the lines are very irregular. Some of the lead domes of Constantinople were melon-shaped, that is having large _convex_ gores. A Turkish example of this remains in an ogee-shaped dome at the angle of the Seraglio wall near St. Sophia. Most interesting works of this tradition are the “domes” or rather domical roofs of St. Mark’s at Venice. Those eastern-looking forms which give such fantasy to it were raised to their present form on wooden framework in the thirteenth century. They are sheeted with plain rolls except the bulb-formed lanterns, which are much like an umbrella in which every gore has a salient angle, a “ridge and valley.” These five timber-framed spire-like domes, erected for their own sake and not lying close to the interior form of the building, in this respect resemble northern spires. The whole group rising over the level front of St. Mark’s is a work of the highest imaginative genius. It is not a building with a dome but a building roofed in domes, bubbling over with domes; and it expresses the metal shrine idea in perfection. The original leaded domes of St. Mark’s were copied from those of the church of the Holy Apostles at Constantinople, a church built by Justinian. At the Renaissance the leaded dome became a popular commonplace especially at Venice. For the most part these were covered like a roof with ordinary rolls. By forming ribs and panels in the wooden foundation a more elaborate but not more successful aspect is obtained. St. Paul’s is well designed in this way. This design with the great ribs Sir Christopher Wren considered “less gothick than sticking it full of rows of little windows” as at St. Peter’s. It was first intended to cover St. Paul’s dome with copper, but £500 was saved by substituting lead at a cost of £2,500. At the National Gallery--a very careful and refined work, one of the last of the old scholarly dead language sort we call classic--the lead covering is formed into raised scales and frets, very well and successfully done of its kind. § VI. OF ROOFS.