STYLE IN ARCHITECTURE. 395 



al'ounded round Rome. This, mixed with hme, made a 

 wonderful hydraulic cement, unequalled until the invention in 

 Ent^iand fifty years ago of Portland cement. 



We have recently heard, on the high authority of Professor 

 Thomson, about the evolution of the human brain from mud. 

 It is probably no less certain that out of this mud ash from 

 the extinct volcanoes in the neighbourhood of Rome has been 

 evolved bv many and slow processes the most intellectual archi- 

 tectural creations of man, the dome and vault of Roman, 

 Bvzantine. Gothic, and Renaissance architecture. 



The gift of Rome to Architecture was the solid vault and the 

 dome. The Egyptians, as we have seen, l)uilt nuid brick 

 vaults. The Greeks and early Romans arched and vaulted 

 their drains. The Cloaca Maxima — the main sewer of Rome — 

 can perhaps claim a small share in the evolution of vSt. Peter's 

 Dome. But these people knew not of the latent potentialities 

 of the vault. But in their need the Romans of the Empire, by 

 the instrument of this cement concrete, made the great dis- 

 covery that the span of their vaults could be increased to an 

 extent that seems wonderful even to us moderns familiar with 

 the use of Portland cement concrete. 



The dome of Hadrian's Bath, now the Pantheon, is of con- 

 crete, and is 150 feet in diameter — a span never surpassed by 

 any other solid dome. 



in the house of the \>stal \'irgins, in the I'^orum, there was 

 a floor of flat concrete, without support. 20 feet square. But 

 the evolution of the luind of man is slow. As Herodotus, I 

 believe, said, " Nothing comes of its own accord to men, but 

 all things by experiment." The Romans, although they could 

 throw a dome over a space 150 feet wide, never conceived of 

 its external but only of its internal beauty; but for twelve 

 hundred years domes were built throughout the eastern world 

 without any attempt to i2;iye external form to the conception. 

 The dome as we know it was a creation of other brains at a 

 later age. 



All the larger Roman buildings were roofed with vaults or 

 domes of concrete, and it is for this reason that so much re- 

 mains of " Eternal Rome." The materials employed suited the 

 labour conditions of the age. The highly-paid freed man built 

 the outside facing of the walls and the centering of the vaults, 

 the cheap or slave labour mixed and filled in the concrete. 

 There is a suggestiveness in the similarity of the Roman con- 

 ditions to our own at the present time in South Africa. We 

 also have highly-paid skilled labour and cheap unskilled labour, 

 and Portland cement and the newly-invented reinforced con- 

 crete as a substitute for Pozzolana concrete, which was used 

 by the Romans. 



Byzantine architecture, named from the style which was 

 popularised by the first Christian Emperor Constantine, in his 

 new capital of Constantinople, though it lasted for centuries 

 after the death of the Roman Empire, was in fact but Roman 

 architecture itself in its later fully developed form. St. Mark's, 

 at Venice, which is 11th centurv Italian, is little advanced in 



