Sydney Observatory time ball

Published by imageservices on June 30, 2008 3 Comments

This shot of the Sydney Observatory time ball was taken at night. The time ball was lit using the existing exterior lights but the building required additional lighting to highlight the brickwork.

Plans for Sydney Observatorybegan as a simple time-ball tower. Every day at exactly 1.00pm, the time ball on top of the tower drops to signal the correct time to the city and harbour below. The original purpose of the time ball was to provide the time to ships in Sydney Harbour. The ball was first dropped on 5th June 1858 and has been dropped regularly ever since.

File #00218642.

Photography by Marinco Kojdanovski.
License: Creative Commons Attribution-Noncommercial-No Derivative Works 2.0

  • Billy

    So what would something like that weigh? I mean im sure it would have been kind of difficult to get the time ball onto thetop of the tower.

  • http://www.powerhousemuseum.com/imagesrvices/ Paula Bray

    Hi Billy

    I will pass this onto the experts at the Observatory and let you know what they say.

  • http://www.sydneyobservatory.com/blog Nick Lomb

    Hello Billy. The time ball is formed of Muntz metal sheeting. Muntz metal is an alloy of copper. One of my colleagues estimated the mass of the time ball from the surface area of the ball, its thickness and the density of the sheeting and obtained an answer of ~200kg. Obviously it would not have been taken up whole, but piece by piece and the Muntz metal sheets riveted together on top of the tower.

    Note that originally the ball was made of zinc sheets nailed on to a wooden framework, but apparently it was not water tight and the framework started to rot. That is when Henry Chamberlain Russell, the director of Sydney Observatory from 1870 to 1905, arranged for the ball to be made of the same metal as the two Observatory’s two telescope domes.