form of fixed railway signal From Wikipedia, the free encyclopedia
One of the earliest forms of fixed railway signal is the semaphore. These signals display their different indications to train drivers by changing the angle of inclination of a pivoted 'arm'.
Seamless Wikipedia browsing. On steroids.
Every time you click a link to Wikipedia, Wiktionary or Wikiquote in your browser's search results, it will show the modern Wikiwand interface.
Wikiwand extension is a five stars, simple, with minimum permission required to keep your browsing private, safe and transparent.