SCIENCE 



[N. S. Vol. XXXI. No. 780 



It was just at this time, when the minds 

 of all were filled with the inventions of 

 Watt and of Stephenson, that Tredgold 

 gave his definition, clearly showing the 

 tremendous influence held at that time by 

 the subject of power. These great develop- 

 ments greatly enlarged the field of engi- 

 neering, and gave birth to a new class of 

 engineer — the railroad engineer. They led 

 also to the differentiation of the mechan- 

 ical engineer from the civil engineer. 

 Since that time the mechanical engineer 

 has claimed as his special field the devel- 

 opment and use of power in all its forms, 

 including the generation of power from the 

 combustion of fuel and the flow of water, 

 by means of the various types of engines 

 and water wheels, the transmission of that 

 power from point to point by means of 

 belting, shafting or other means, and the 

 utilization of that power by machinery. 

 There is hardly a field of human industry, 

 therefore, which is not dependent upon the 

 mechanical engineer, because all manu- 

 factured articles depend upon power in 

 some application, and upon machinery 

 operated by power. The field of the mod- 

 ern mechanical engineer, however, not only 

 covers the department of power and its ap- 

 plications — in manufacturing, in the steam 

 locomotive, in the steamship — but it is 

 also held to include the construction of 

 mills, and all applications of steam and 

 heat, such as heating, ventilation, lighting, 

 refrigeration, ice making, elevators and so 

 on. 



But notwithstanding the differentiation 

 from it of the field of the mechanical engi- 

 neer, the field of the civil engineer was 

 itself enlarged by the progress of science 

 and invention. The great impetus given 

 to manufacturing rendered necessary the 

 distribution of the raw material and of the 

 manufactured products. Transportation 

 engineering was enormously increased in 



its scope, and the new profession of the 

 railroad engineer was brought into exist- 

 ence. Roads and canals, harbors and docks 

 were built with unexampled rapidity and 

 river improvements Avere extensively car- 

 ried on. At this time the increasing use of 

 canals gave occasion for the celebrated re- 

 mark of Brindley, the great canal engineer 

 of England, himself an untutored genius, 

 who, when asked what the use of a river 

 was, replied "to supply canals with 

 water." At the same time the economical 

 production of wrought iron rendered pos- 

 sible the construction of bridges of unex- 

 ampled span. 



By this time had begun one of the great- 

 est sociological movements which charac- 

 terizes the present time, namely, the in- 

 creasing congregation of people in cities. 

 At the beginning of the nineteenth century 

 only 3 per cent, of the population of the 

 United States lived in cities, while at the 

 present time the urban population is over 

 33 per cent, of the total. This phenome- 

 non, during the last half of the century 

 just passed, has led to the differentiation 

 of another field of engineering, namelj', 

 that of the sanitary engineer, whose spe- 

 cific province it is to deal with the prob- 

 lems of water supply, drainage, the dis- 

 posal of refuse, the purification of water 

 and sewage, the sanitation of dwellings, 

 and the various other problems resiilting 

 from this congestion of population. 



Improvements, also, in chemistry and in 

 metallurgy, have given rise to still other 

 distinct branches of engineering, namely, 

 mining engineering and metallurgy, the 

 scope of which I will not endeavor here to 

 sketch. 



Again, the field of the mechanical engi- 

 neer has during the past quarter of a cen- 

 tury become subdivided, owing to the dis- 

 coveries in electricity. Steam and water 

 are no longer used simply to propel steam 



