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ECONOMIC GEOLOGY 
Good ferro-concrete is so strong that the wall spaces are 
not distorted and the building sways like a box. A census 
of the damage wrought by the Tokyo Earthquake showed 
that of 592 ferro-concrete buildings 78 per cent. were un- 
damaged, and only 1-3 per cent. collapsed. The movement 
causes the rectangular spaces in a steel framework to become 
rhomboids, and if the partitions are of weak material, such 
as lath and plaster, they are cracked and crushed in the 
distorted frame.