578 CIVIL ENGINEERING 



But the selection and preparation of suitable materials for struc- 

 tures are details which rather belong to the domain of the chemist 

 and physicist than to the engineer whose province it is to design, 

 assemble, and direct work, whereby he may more generally apply 

 the resources of nature to the wants of man. 



Fuel 



For this purpose, power is a fundamental factor, and for many 

 years it was readily derived from the forests, so generously dis- 

 persed over the earth; but the rapid increase in the demand for 

 all classes of motors as well as for domestic and structural pur- 

 poses has threatened an early exhaustion of this supply. For 

 locomotives, it soon became impracticable, while for the modern 

 steamship it would be absolutely impossible. With the discovery 

 of coal and its stored energy, the world was revolutionized. The 

 first quarry for anthracite was opened at Summit Hill, Pennsylvania, 

 in 1792, but the cost of hauling to the market was such as to pro- 

 hibit its use. Thus was stimulated the construction of the Lehigh, 

 Schuylkill, and Union canals and the Switchback Railroad early 

 in the last century, the progenitors of our extensive system of pub- 

 lic works, which has been developed by private capital and enter- 

 prise with occasional aid from local and general governments mntil 

 the railroads of the country now exceed 215,000 miles, represent- 

 ing a capital of over 14,000,000,000 dollars and carrying over 1,- 

 200,000,000 tons of freight per annum, at an average cost of 7.6 

 mills per ton-mile. 



The rapid increase in the demand for anthracite coal from the 

 Schuylkill and Lehigh regions resulted in a maximum yield, for 

 some years, of 65.000,000 tons per annum; but the discovery and 

 working of large deposits of soft coal in West Virginia and many 

 other localities, as well as the greater cost of mining, has reduced 

 the output of hard coal to about 59,000,000 tons, with resulting 

 increase of price, while the bituminous mines are now furnishing 

 260,000,000 tons. This, with the opening of the free-working iron 

 ores of Lake Superior and the exceptionally cheap transportation 

 on the Great Lakes, has concentrated the mammoth iron and steel 

 plants near their borders and given to the world a new stimulus 

 in structural materials. Coke, natural gas, and petroleum have 

 also aided in the general movement for cheaper power, and the 

 generation of artificial gas, as the most effective form of energy, 

 has proceeded, pari passu, with the demand for greater economies. 

 Attention is now being concentrated upon the utilization of the 

 dynamic agencies of the earth, found in her water-courses, atmo- 

 sphere, and electricity, to great advantage for the generation and 



