of stone inserted in the concrete while it was still soft.  The huge vaults and arches affected by the Romans made concrete a particularly convenient material, and nothing could better illustrate its strength than the tenacity with which it has endured the strain in the unsupported portions of the vaults of the Basilica of Constantine.  Any of the more imposing buildings which were not mainly of concrete were composed of blocks of stone, held to each other by clamps soldered in with lead.  Few, if any, such buildings were made entirely of marble.  In the case of those composes of the other varieties of stone already named, the surface was commonly coated either with stucco or with marble facings attached by hook-like clamps fixed into the main structure Externally the appearance of Rome—­so far as its public buildings are concerned-was that of a city of marble.  The present having been for centuries torn away, either to be used elsewhere, or more often to be burned down for lime.

[Illustration:  FIG. 28.—­BUILDING MATERIALS. (From Middleton.)]

CHAPTER IX

THE ROMAN TOWN HOUSE

We have taken a general survey of the city of Rome, its open places, streets, and public buildings.  We may now look at the houses in which the Romans lived, and at the furniture to be expected inside them.

Mention has already been made of the large and lofty tenement houses or blocks, often mere human rookeries, which were let out in lodgings to those who did not possess sufficient means to occupy a separate domicile of their own.  These buildings, which were naturally to be found in the busier streets and more thickly inhabited quarters, were not, however, the habitations most typical of the romanized world.  They were created by the special circumstances of the city, and might recur in other towns wherever the conditions were similar.  The cramped island part of Tyre, for example, possessed houses even loftier than those of Rome.  Where there was sufficient room—­that is to say, where there was no large population crowded into a space limited by nature or by walls of defence—­the ordinary house was of a very different character.  It was built on a different plan and seldom ran to more than two stories, if so high.  We shall shortly proceed to describe such a house; but it is first desirable to say something more of the tenement “block” in the metropolis.  It is to be regretted that no such building has actually come down to us; we are therefore compelled to form our notions of one from the scattered references and hints of literature.  Nevertheless if these are read in the light of customs still observable in Rome itself and in other parts of Italy, the picture becomes fairly definite.