Stringers,

sections; 186, 206

spacing, 192, 194

"Structural" defined, 314

Structural metal, price of, 23

Structure, general features of, 120

Student competition on cost estimating,

141, 146-149

Study of engineering economics,

importance of, 3

Subpaving or base, 189

Subpunching, 211

Subpunching and reaming versus

punching full size, 202

Substructure,

economics, 167-174

influence on arch economics,

238-243, 245

Sunken logs, 172

Superintendent, 383

Supplies, 384

availability of, 123

Supply of labor, 373

Supporting,

cables for vertical-lift bridges, 295

machinery parts, 314

structure, 314

Surveying instruments, 382

Surveys, copying of, from field books, 381

Suspended span in cantilever bridges,

economic lengths of, 258

Suspending floor from backstays, 266

Suspension bridges, 25

anchorages, 94, 267

approaches, 266

best system of cancellation for

stiffening trusses, 265

buckle-plate floor, 263

cantilever bridge comparison, 90-112

decks, 263

economic dimensions, 95

economics, 263-283

panel lengths in, 265

rise of cables, 265, 266

truss depths, 265

ends of stiffening trusses

free or anchored, 265

erection, 401

eye-bar cable, quantities of various

materials in, 278

floor-system, 263

formulae for weights, 273-275

intermediate trusses and cables, 264

legitimate function, 263

limiting widths of structure, 94

military bridging, 469

nickel steel floors, 264

prices, 25

quantities for wire cables, 276

stiffening trusses, 265

weights of alloy-steel eye-bars, 277

"Suspension Bridges and Cantilevers—

Their Economic Proportions and

Limiting Spans," 90

Swiftness of current, 483

Swing spans, 298

bascule or vertical-lift

comparison, 284, 285

combined rim-bearing and center-

bearing type of, 288

comparative economics of, 308

economics of, 287

Symmetry, 209

System of contract-letting, ideal, 343, 344

Systemization, 18

T

Tabulation of economic span-lengths, 160

Talking among employees, 358

Technical book writing an

extravagance, 486

Technical schools, study of

economics in, 3

Temperatures suitable for painting, 448

Templet shop, 379

Templets, reaming to, 205, 215

Temporary bridges, 21

Temporary economic expedients, 15

Temporary piers in Missouri River, 168

Tests,

alloy steels, 38-43

cement, 380

members in full-size bridges, 138, 139

Thickness of web, 207

Three-hinged versus hingeless

arches, 229

Three-hinged versus two-hinged

arches, 238

Three-span structure, economic

investigation of, 165

Through bolts in military bridges, 477

Thrust of braked trains, 140

Thrust of earth, influence of, 228

Tides, 122

Tie-plates a necessity, 182

Tie-plates versus lacing in

riveted tension members, 207

Ties,

highway bridge floors, 192

street car traffic, 425

treated, economics of, 182

Timber,

bridges,

fire protection, 420

repairs, 419

roof-protection for, 420

decks, 184-195

concrete for highway bridges,

comparison with, 187

growing scarcity of, 22

military bridges, 475

prices, 23

steel for concrete forms,

comparison with, 170

treatment, 183, 188