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The historian pointed to the restored ball signal and explained how its painted wooden spheres warned engineers of approaching trains.
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The historian pointed to the restored ball signal and explained how its painted wooden spheres warned engineers of approaching trains.
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Related words
ball signal
Noun
historical
Japanese Meaning
（歴史的）初期のアメリカ鉄道で使用された、木製の球を上下させることで信号を表示する機械式信号装置。球は様々な色に塗装され、ロープと滑車を用いて操作される。
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