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出典:Wiktionary
time-ball (複数形 time-balls)
出典:『Wiktionary』 (2010/04/01 13:24 UTC 版)
time ball (複数形 time balls)
出典:Wikipedia
出典:『Wikipedia』 (2011/06/22 14:12 UTC 版)
A time ball is a large painted wooden or metal ball that drops at a predetermined time, principally to enable sailors to check their marine chronometers from their boats offshore. Accurate timekeeping is one way of enabling mariners to determine their longitude at sea.
名詞の変化形:
time-ball