Hornsby Water Clock, Water clock sculpture in Florence Street mall, Hornsby, Australia.

The Hornsby Water Clock, titled Man, Time and the Environment, is a kinetic sculpture and fountain in the Florence Street pedestrian mall in Hornsby, New South Wales. It stands about 8 metres tall, weighs 20 tonnes, and is built of bronze, stainless steel and glass. It combines a Greek clepsydra, a Chinese water-wheel clock and a Swiss pendulum clock, all mounted on a rotating pontoon.

Victor Cusack designed the sculpture and built it with foundry floor manager Rex Feakes in bronze, stainless steel and glass. Construction, including changes to the Florence Street mall, took two and a half years and cost over A$1 million; it was unveiled in 1993. Discarded chicken bones and other rubbish caused repeated breakdowns until the water filtration system was upgraded.

The clock face marks the hours with the letters of "Dare we forget" instead of numbers, and the sculpture is decorated with Aboriginal art forms as a reminder that Hornsby once held a strong tribal population. Twelve animals appear on the work, among them the tawny frogmouth, rainbow lorikeet, pied cormorant, little penguin, Australian pelican, water dragon, blue-tongued lizard, goanna, grey-headed flying fox, brushtail possum and white-bellied sea eagle.

The sculpture stands in the open-air Florence Street pedestrian mall, so it can be walked around and viewed at any hour without a ticket. The pontoon turns once every 12 hours, so the pointer's position against the Roman numerals in the basin changes only slowly; the carillon and the moving parts are the quicker things to watch.

The clock face marks the hours with the letters of "Dare we forget" instead of numbers, and the pendulum weight is 350 kg, heavier than that of the Great Clock of Westminster, whose 4-second cycle it shares. The design follows a 1669 drawing by Claude Perrault that was never built.