“ The plaintiff, a locomotive engineer, sued for personal injuries resulting from a collision with a freight train which had been left standing, without danger signals, on the track in the defendant's railroad yard at Thurber Junction, Texas. The company contended that he had been guilty of contributory negligence in failing to keep a lookout, in running at a high rate of speed, and disregarding rules requiring the engineer to keep the locomotive under control in anticipation that cars might be on the tracks within yard limits. ”