THE POLK SYSTEM 9 



Short Story About 

 Concrete 



T^GYPTIANS. On the top of the huge pyramids of Egypt 

 I* there are enormous blocks of stone of such size that modern 

 engineers wonder how they ever were put there. They are well 

 preserved and show little effect of the 4,000 years weathering they 

 have undergone. Recent investigation on the subject of this vast 

 engineering feat seems to show that those huge stones were prob- 

 ably carried there in water pails or some similiar contrivances. 

 The Egyptians knew how to make a hydraulic cement, and pieces 

 of wood found within these big blocks together with the conglom- 

 erate structure seem to show that they made use of their secret 

 in the erection of the pyramids. 



GREEKS and ROMANS. The Greeks also knew about 

 cement. Many of their walls and slabs of stone which have until 

 recently been supposed to be solid rock, have proved to be exam- 

 ples of an enduring concrete construction. The Romans built the 

 best roads that man has ever known. They dug to solid rock, 

 filled in with crushed rock, bouldei's and pebbles, and then coated 

 the top with a hydraulic cement. Over this they put paving 

 stones. The paving stones have worn away and crumbled to dust, 

 but the concrete mixture remains stronger than it was the day it 

 was put there. Fallen columns, pillars and arches of concrete con- 

 struction among Roman ruins show much better lasting qualities 

 than the hardest marble that was used for mural decoration. 



In this connection the Architecture Record issue of February, 

 1909 says: 



"The Romans mixed their' concrete exactly as we mix ours- in 

 a general batch that is, stones, cement and lime were mixed to- 

 gether and thrown into a wooden form, precisely as we do it to- 

 day. The marks of the wooden forms are at all times discernible, 

 and especially is this so in the corridor of the house of Augustus 

 on the Palatine (P. 10) where the grain of the wood can be clear- 

 ly seen. These walls are some twenty-four feet above the ground 



' 'They are not built of piece* , and they 

 cannot go to pieces. 



