CHAPTER II 



THE MACHINES OF THE ANCIENT WORLD 



IN the homes of the earlier civilizations are buildings 

 and monuments which have withstood the ravages of 

 time and the waves of hostile invasion. Often these 

 records of man's earlier activities are only restored to 

 sight by excavation, for they have been covered by the 

 dust of succeeding ages. The temples and palaces, 

 the city walls, and the monuments of Egypt and Asia 

 were of stone or brick, but the houses of the common 

 people were usually of mud. When a conqueror razed 

 a city, holes were broken in the walls to render it less 

 easily defended ; the monuments of the kings and the 

 altars of the local gods were toppled over; and the 

 houses of the common people were reduced to dust. 

 The large buildings, of course, took years to restore, 

 and the weakened and terrorized inhabitants may have 

 hesitated to rebuild what had so recently been de- 

 stroyed by their enemy. Thus in time the traces of a 

 city were lost beneath the mud and rubbish of succeed- 

 ing generations. 



Such relics as we have, suggest to the engineer of 

 to-day the question : How did the ancients, with their 

 limited knowledge of physical science, succeed in 

 erecting such enormous and high structures? The 

 answer is to be seen partly in their knowledge of certain 



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