Australia or Australasia

I doubt not it will have been noticed by many that in the numerous despatches and telegrams that of late have been passing between the Imperial Government and the Australian Governments relative to federation, two words constantly appear as designating this portion of the globe "Australia" and "Australasia," and they seem to be used by all parties alike as convertible terms, frequently presenting themselves in the same document as, if so used, for the purpose of avoiding tautology. A little reflection, however, will show that these terms are by no means one and the same.