…The Observatory Time-Ball

Time Signal

The first public time signal was broadcast from  the roof of Flamsteed House in 1833. The idea of dropping a ball at a predetermined time was the brainchild of Captain Wauchope, RN, and was tested at the Naval College at Portsmouth before Maudslay & Field were commissioned to install the first Greenwich time-ball in that year.

The signal was (and is) given at 1 p.m. because the astronomers would be busy checking the rates of their clocks against the sun’s transit at noon. At 12.55 p.m. the ball is hoisted half-way up the mast – originally a signal for navigators on ships in the Thames and London docks to be ready.  At two minutes to the hour the ball is hoisted to the top of the mast and then drops precisely at 1 p,m. From this, sea captains about to sail could check the rate of their marine chronometers, which were in wide use by the 1830s.*

Time Signal

*From the Royal Observatory Greenwich Souvenir Guide

8 Comments CherryPie on Sep 10th 2014

8 Responses to “Distributing Time…”

  1. james higham says:

    Used to visit that two or three times a week. I lived across the road.

  2. Never heard of it. reminds me of the ball in time square, drop New Year Eve. In New York City.
    Coffee is son

  3. Amfortas says:

    The ball was especially designed to drop taking account of variations in global warming. On cold days the ball retracted.

  4. Steve Hayes says:

    I’d heard of a noon gun before, but this was new to me.

  5. I love the idea of this ball setting time around the waterways and area….stunning image.