The general purpose tool of the Australian Aborigines, usually known as a stone axe, is more correctly termed a hatchet since it conforms to the design requirements of a tool made for one-handed use. Similar implements not so conforming appear to be special purpose tools. A geometrical feature, common to all these tools and perhaps to other types, is the medial plane which determines the position of the edge and governs some of its operational properties. Some dynamic features of stone hatchet heads, the design of handles for them, and their security of mounting are examined and compared with the features of modern steel hatchets. -- AATA