564 CIVIL ENGINEERING 



dynamics; electricity; the laws of wave-motion; the reflection, 

 refraction, and transmission of light; and the mass of other data 

 furnished by the physicist form a large portion of the first prin- 

 ciples of civil engineering. 



The function of applied mechanics is to establish the fundamental 

 laws of physics in terms suitable for service, and to demonstrate 

 their applicability to engineering construction. 



Chemistry is a science that enters into closer relations with civil 

 engineering than does any other science except mathematics and 

 physics, and as the manufacture of the materials of engineering 

 approaches perfection the importance of chemistry to engineers 

 increases. Within a comparatively short period the chemist has 

 made it possible by analyzing and selecting the constitutents to 

 control the quality of cast-iron, cast-steel, rolled-steel, bronze, brass, 

 nickel-steel, and other alloys. The engineer requires certain phys- 

 ical characteristics in his materials, and obtains them by limiting 

 the chemical constituents in accord with data previously furnished 

 by the chemist. The proper manufacture of cement requires the 

 combined skill and knowledge of the chemist and the mechanical 

 engineer. 



In water-supply the chemist is called in to determine the char- 

 acter and amounts of the impurities in the water furnished or con- 

 templated for use. The recent discovery that the introduction of 

 about one part of sulphate of copper in a million parts of water 

 will effectively dispose of the algae, which have long given trouble, 

 is a notable instance of the increasing interdependence of these 

 two branches of science, as is also the fact that the addition to 

 water of a small amount of alum will precipitate the earthy matter 

 held in suspension without leaving in it any appreciable trace of 

 the reagent. 



In the purification of water and sewage, in the selection of ma- 

 terials which will resist the action of acids and the elements, and in 

 the manufacture of alloys to meet various requirements, a thorough 

 knowledge of chemistry is essential. 



A knowledge of mineralogy is requisite for a clear understand- 

 ing of the nature of many materials of construction, but is other- 

 wise of only general interest to civil engineers. 



Geography in its broad sense is related to civil engineering in 

 some of its lines, for instance, geodesy and surveying, but gen- 

 erally speaking there is not much connection between these two 

 branches of science. 



Astronomy is perhaps more nearly related to civil engineering 

 than is geography, although it is so related in exactly the same 

 lines, for the railroad engineer on a long survey must occasionally 

 check the correctness of his alignment by observations of Polaris, 





