Lighthouses of Australia Inc

The White Lighthouse at Queenscliff	The Black Lighthouse at Fort Queenscliff	The Point Lonsdale Lighthouse

The White Lighthouse and the Hume tower, with Point Lonsdale Lighthouse in the distance
Photograph: Ed Kavaliunas

From left to right: the Murray Tower, the White Lighthouse, the Hume Tower, a flagpole in Fort Queenscliff, 
the Black Lighthouse, the Signal Station in Fort Queenscliff and a water tower 
Photograph: Ed Kavaliunas

Operation of High and Low Lights

About the original operation of the high and low lights, ET Raison in his book, "Lighthouses at Port Philip Heads", states:

The new high light was continuous white light as was shown in the old sandstone lighthouse, but the new lower light had white and red sectors to assist mariners to determine their position. As ships approached the Heads, a white light showed below the white, upper light, and as the ship advanced, it moved into the red sector of the lower light. While the red light was visible below the white light, the ship was in the channel and could safely enter the bay.

... a steel structure, known as the Hume tower, was erected to the west of the lower light which indicated the western extremity of the new channel when viewed in line with the upper light. In May 1974 another steel structure, known as the Murray Tower, was erected to replace the obelisk (on the eastern side) which was demolished soon after. The lights on both towers operate in unison with the lower light.

This is demonstrated on Rod Cairns' excellent page, Leading Lights at Port Phillip Heads.