324, 325 Tabulating machines, 320, 321, 322, 323,

machines for cards, 323 Tacks, celluloid-covered, for maps, 247,

map, 225, 247, 248 Tarr and McMurray's new geographies,

Taylor, Graham Romeyn, 214, 221 Telephone load curves, 108

rates, 126

service curves, 179

service in Wisconsin, 178 Telephones in United States, pin map,

number used in United States, 354 Temperature curves, 117, 118 Thompson, A. T. & Co., reflectoscope, 303 Thomson, H. F., 198 Three-dimensional charts, 205, 206 Time charts, 53 Time-distance charts, 64, 67

curves, 64, 67 Titles for charts, 344, 345 Topographical maps, 235 Totalizing curves, 125 Tracing cloth used with maps, 210 Trading centers in United States, 238 Train-dispatching charts, 61, 62, 67 Train-operation curves, 123 Transparentizing solution, 328 Trenton, N. J., public schools, 2 Trucks, costs for gasoline, 198

cost of operating, 29 Tuberculosis death rates, 351 Tug-boat operation, 58 Turbine, steam, tests of, 122 Two independent variables, charts for, 205,

Union Bag & Paper Co., 45

Union Pacific Railroad, 311, 312

United States Census Office methods, 320,

United States Steel Corporation, 313, 314 University of Cincinnati, 46, 47, 229, 231

Vacation chart, 53 Variables for curves, 84 Variables, two independent, 333 Velocity of water in streams, 87 Vertical arrangement of curves, 347, 349

bar charts, 354

bars, 46, 47

for components, 138

Wage charts, 180, 181, 182

comparison on railroads, 49 Wall board, 232

charts, 306

exhibits, 358

maps, 225, 229 Wall Street Journal, 308 Warne, Frank J., 103 Water power in United States, 216 Water storage-capacity curves, 159 Wave lengths on curves, 283 Waves in curves, 97 Wavy line for bottom of chart, 350, 352,