The bright red Time Ball on the top of the Royal Observatory is one of the world's earliest public time signals
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The bright red Time Ball on top of Flamsteed House is one of the world's earliest public time signals, distributing time to ships on the Thames and many Londoners.
The Time Ball was first used in 1833 and still operates today. Normally each day, at 12.55pm, the time ball rises half way up its mast. At 12.58pm it rises all the way to the top. At 1pm exactly, the ball falls, and so provides a signal to anyone who happens to be looking.
Of course, if you are looking the wrong way, you have to wait until the next day before it happens again. The time ball drops at 1pm GMT during the winter months and 1pm BST during the summer. Please note: the time ball will not operate if the weather is too windy.