送交者: outsider 于 2005-1-12, 22:56:35:
回答: 同经目的是为了保证两地中午是同时 由 HunHunSheng 于 2005-1-12, 19:28:58:
on same longitude, and you don;t know the difference in longitude, then how do you measure?
You can find another point along the longitude by following the compass or polar star.