The Evolution of Architecture. 333 



second century B. c. that the cross-vault with its important 

 corollaries, the apse and dome, gave an immense extension 

 to those possibilities of internal grandeur which were to the 

 Roman all that the possibilities of external beauty were to 

 the Greek. And it was with bricks and mortar that these 

 possibilities were realized. The Romans were essentially a 

 brick-building people, and the loss of their great art of mak- 

 ing an adhesive, binding mortar was one which to later 

 builders was incomparably great. Marble in Rome was very 

 scarce indeed, andjjsecLfef little else than ornament outside 

 and in. 



Sewers and aqueducts were the first colossal works in 

 which the Roman passion for the useful found expression. 

 The first great aqueduct, however, was more than two cent- 

 uries later than the first great sewer, the Cloaca Maxima. 

 The next four hundred years (from 300 B. c. to 100 A. D.) 

 saw thirteen of these gigantic works threading the Campag- 

 na, some of them bringing their crystal flood from mount- 

 ains forty miles away, and they still bring it (some of them) 

 after the lapse of some two thousand years. The great city 

 did not need a third of all the water they brought for its 

 necessities. It needed all the rest for its eight hundred and 

 fifty private baths, opened to any one who could pay the 

 modest price, and the great imperial baths that welcomed all 

 alike without a fee. The present Pantheon is the best pre- 

 served of all the imperial baths, though what is left is mere- 

 ly the great central hall, one of the noblest interiors in the 

 world. The grandeur of this was much exceeded by the 

 baths of Caracalla and Diocletian, the latter capable of enter- 

 taining three thousand bathers at once. From the love of 

 pleasure and the admiration for physical courage and the 

 political necessities of the times " Panem et circences " 

 came the whole system of buildings of which the theatre of 

 Maxentius, the Circus Maximus, and the Flavian Amphi- 

 theatre or Colosseum are great examples ; triumphs of con- 

 structive energy and skill, incrusted with architectural co- 

 lumnar ornaments, having no structural function to perform. 

 Such monumental columns as those of Trajan and Marcus 

 Aurelius are as peculiar to herself as anything that Rome 

 can show. The triumphal arch is almost equally her own. 

 It is her own as being a massive building with a decorative 

 screen ; her own as an expression of her conquering zeal and 

 pride. The pyramids of Egypt do not tell the story of their 

 origin in the burial mound more clearly than the arch the 



