INGENUITY AND LUXURY 



in the course of construction, many precautions are 

 taken to see that this steel frame is protected at every 

 point, there is always a possibility that some joint 

 or crevice will be overlooked and left exposed. Even 

 the smallest crack that would admit moisture might, 

 in time, be the undoing of the strongest steel structure, 

 since the strength of the skyscraper lies in its steel 

 frame. This possibility, among other things, has made 

 the builder look to other materials as possible sub- 

 stitutes for steel; or for a permanent preservative that 

 might be applied to the surface of the metal. 



Paint is a very good preservative, although in order 

 to give perfect protection it must be applied to the 

 steel at comparatively frequent intervals. This is 

 perfectly practical in such structures as bridges where 

 the metal is exposed, but is out of the question in 

 steel-frame buildings. And so the constructor of 

 such a building must have a haunting fear that his 

 most dreaded enemy may be gnawing insidiously into 

 the very vitals of his structure, without giving him a 

 chance to protect himself, or to detect the attack. 



In looking about for some permanent protective 

 for steel, it was discovered, curiously enough, that 

 moistened Portland cement, or "fat" concrete, answered 

 this purpose almost perfectly. Steel embedded in 

 concrete will outlast the centuries. What could be 

 more natural, or more ideal, therefore, than to combine 

 these two substances as building materials? The 

 experiment was tried, and the era of "reinforced con- 

 crete," or "concrete steel," as some enthusiasts call it, 

 was inaugurated an era which seems likely to prove 



