Oost Indien from the Sea Atlas of 1666 by Pieter Goos.
The Cocos (Keeling) Islands are directly above the middle mast of the
ship on the left edge of the stamp. The coast-line of Australia had
not yet been completely mapped, and (although it is not shown on the
stamp) New Guinea was thought to be connected to Australia at Cape
York on the east side of the Gulf of Carpentaria.
The cachet on the
Australian cover is based on the same map by Pieter Goos.
stamp from Christmas Island covers a very small part of the same map.
It shows the island of Java and the city of Batavia (Jakarta).