CHAPTER XXI.

254. Introductory 320 255. Train Resistances 322 256. Grades 322 257. Curves 324 258. Resistance of Curves and Compensation in Grades 324 259. Transition Curves 325 260. Road-bed, including Ties 327 261. Mountain Locations of Railroad Lines 328 262. The Georgetown Loop 331 263. Tunnel-loop Location, Rhætian Railways, Switzerland 331