Civil engineering 229 History 83 Geology 60 Education 55 Bridges 50 Study and teaching 44 Water-supply 42 more ... Coal mines and mining 37 Sewerage 33 Mining engineering 32 Mechanical engineering 31 Public schools 28 Truss bridges 26 Railroads 25 Teachers 23 Curricula 22 Railroad bridges 20 Design and construction 19 Industrial arts 19 Iron and steel bridges 18 Universities and colleges 18 Street-railroads 17 Research 16 Economic conditions 15 Geology, Stratigraphic 15 Finance 14 Attitudes 13 Water 13 Collective bargaining 12 Groundwater 12 less ...