2110 - Model Time Ball (circa 1911)

This item is no longer on display in the museum.

Time Balls were traditionally sited at ports to allow ship's navigators to accurately synchronise their chronometers by observing the fall of the ball at 1pm each day.

There is one, no longer operating, on the top of the Old Windmill in Wickham Terrace in Brisbane. Sydney Observatory still operates theirs every day.

In 1910, the Synchronome Company in London installed a four foot diameter time ball on Kingsway Hall in London. Raised and dropped every hour on an electrical signal from Greenwich Observatory, it was touted as 'the only automatic time ball in the world'. At that time, they released a 'small working model' that would form 'a most attractive shop window novelty' for watchmakers and jewellers.

One was  supplied to Prouds Ltd in Sydney, as evidenced by a photograph sent to the Synchronome Electrical Co. of Australasia in Brisbane in 1916.

In 2007, its remains were passed on to Norman Heckenberg and Anthony Roberts by the family of the late Lawrence Tapprel, who had been an apprentice at Prouds before WW2 and who had saved many relics of the company's operation.

The ball, motor, a worm, a coil and the glass dome were all lost, so extensive restoration has been required to return the unit to working order.

It operates in the following way: some minutes before each hour, a program timer connects a battery to the motor. Through a double worm gear, it slowly drives a brass spool through a spring-loaded clutch. The spool takes up a line that runs up to the platform at the top of the tripod, over a small pulley (hard to see at the back) and down to the bottom of the stem carrying the ball. As the ball reaches the desired height, the line trips a small knife switch on the platform, stopping the motor. The ball is then held, ready to fall.

On the hour, a current pulse from a master clock energises the two electromagnets on the left, attracting the steel plate of the clutch, thereby releasing the spool so that the ball can drop freely. At the end of its fall, it closes the knife switch, allowing current to flow to the motor at the next hour when the process is repeated.