12 



THE POLK SYSTEM 



ing to compare with the highly developed Portland cement of to- 

 day, yet they did imperishable work. Strange to say, the people 

 of the medieval times lost the secret and all the fine architectural- 

 work of the "dark ages" is fast crumbling into oblivion. Not un- 

 til the opening of the 

 nineteenth century did 

 man again become in- 

 terested in means of 

 making artificial stone. 

 The modern searcher 

 after the secret, how- 

 ever, turned his at- 

 tention to the produc- 

 tion of a fine powder 

 that would do the ce- 

 menting when mixed 

 with rock and water. 

 He wanted a much 

 smoother and neater 

 result than the ancient 

 builder. In England, 

 Germany, and France, 

 chemists and engineers 

 worked on the produc- 

 tion of a dependable 

 cement from 1790 un : 



til 1850 before they made one that fulfilled the requirements. In 

 1865 the first Portland cement was brought to the United States, 

 and in 1872 the first home-made product was put on the market. 

 In 1880 the output of all factories in our country was only 82,000 

 barrels. In 1896 it had passed the million mark, and in 1909 it 

 was sixty millions. That's the way America does things. Today 

 there is practically no foreign cement for sale on our markets. 



Today we stand on the threshold of the concrete age. The 

 possibilities of a concrete construction are numberless from the 

 sewer to the tip-top of the sky-scraper re-enforced concrete is 

 displacing all other forms of masonry and building materfal. En- 

 gineers are doing with concrete, things that we did not -dream 



Twin Concrete Silos on farm of Frank White, La Fox, 111., each 



18x45 feet. Built by Polk System. W. H. Warford, 



Geneva, 111., Contractor. 



''They are not built of pieces and they 

 cnnnot go to pieces. 



