THE MODERN SKYSCRAPER 



mediaeval castle, the highest occupied structures of 

 the Middle Ages, was the product of danger. 



But in modern times, since houses are no longer fort- 

 resses, economic reasons alone have forced builders to 

 add more and more stories to their structures. Prac- 

 tical constructors roughly calculate the cost of a building 

 by the spread of its roof, not by the number of its 

 stories. It requires no more land, no larger founda- 

 tion, and no more roofing material to erect a five-story 

 building than to build a one-story structure of corre- 

 sponding horizontal dimensions. And while, of course, 

 every added foot of height adds to the cost of con- 

 struction, this cost is far less than if the increase in 

 size were in a horizontal instead of in a vertical direction. 



During the first half of the nineteenth century the 

 "normal height" of buildings in the country, small 

 towns, and villages, was two stories; in the larger 

 cities three, or even four, stories; and in the largest 

 cities, five stories, except for ornamental purposes. 

 At that time cities were relatively small and the per- 

 centage of persons living in the country relatively 

 large. But the last half of the nineteenth century saw 

 the people crowding into the larger cities in ever in- 

 creasing numbers, focussing on certain centers, and 

 overcrowding many districts so that the price of land 

 in such places rose to fabulous figures. As a result 

 it became necessary either to dig cellars deeper, raise 

 roofs higher, or do both, to accommodate the popu- 

 lation. 



But now man's physical limitations offered an ob- 

 stacle to unlimited vertical extensions in building con- 



