Places to the east start their day sooner than places to the west. When travel and communication were slow, time differences were of little importance, and most towns in Britain used local time. In the early 19th century, construction of the railways began, and telegraph by wires became common. And local time became a great inconvenience especially for the rail ways, the telegraph companies and the Post Office. In 1840, the Great Western Railway ordered that London time be used at all its stations. By 1855 most publics clocks in Britain were set to London time. It is the time at the greenwich Observatory, from which came the name Greenwich Mean Time. 잘못된거 the Great Western Railway ordered that London time be used at all its stations. --> the Great Western Railway ordered  London time be used at all its stations. It is the time at the greenwich Observatory, from which came the name Greenwich Mean Time. --> It is the time at the greenwich Observatory, which came from the name Greenwich Mean Time. or It is the time at the greenwich Observatory, from which the name Greenwich Mean Time came . 이거 아냐?