CHAPTER XXII.

264. Railroad Signalling 335 265. The Pilot Guard 335 266. The Train-Staff 335 267. First Basis of Railroad Signalling 336 268. Code of American Railway Association 337 268_a_. The Block 338 269. Three Classes of Railroad Signals 338 270. The Banner Signal 338 271. The Semaphore 340 272. Colors for Signalling 340 273. Indications of the Semaphore 341 274. General Character of Block System 342 275. Block Systems in Use 343 276. Locations of Signals 344 277. Home, Distant, and Advance Signals 344 278. Typical Working of Auto-controlled Manual System 345 279. General Results 348 280. Distant Signals 349 281. Function of Advance Signals 349 282. Signalling at a Single-track Crossing 350 283. Signalling at a Double-track Crossing 352 284. Signalling for Double-track Junction and Cross-over 352 285. General Observations 353 286. Interlocking-machines 354 287. Methods of Applying Power in Systems of Signalling 357 288. Train-staff Signalling 358