Regulator clock, Robert Ellery, Melbourne, 1888

Astronomical regulator clock designed by Government Astronomer Robert Ellery and built at Melbourne Observatory in 1888. The clock was probably made by Observatory instrument maker Carl Otto. Ellery designed this clock to send time-signals by telegraph line from Melbourne Observatory to the time-ball at Williamstown.

The time signal dropped the time-ball precisely at one o'clock each afternoon, thereby enabling ships's officers in the port to check the rate of their chronometers. Ellery designed the clock so that it would give a prolonged electrical contact, thereby generating an appropriate electrical signal. 'I therefore designed a controlled pendulum clock, in which the pendulum drives the seconds wheel and hand, and thence the minute and hour hands.

The seconds wheel closes contact springs in the usual way as each tooth passses, but, as the motion of the wheel is slow as that of the pendulum, the contact is sufficiently prolonged to obviate all difficulty complained of as regards adjustment of line relays.' Report of the Government Astronomer, 1888, p. 6. Weight driven; deadbeat escapement. Pendulum has steel shaft with cylindrical brass bob.Separate dials for minutes, seconds, and hours.