I rather like Air Mail stamps of the world, used on airmail covers (of course), which logically is why they were issued. The sight of the familiar blue and red bordered airmail envelope emits a subliminal message, evoking images of distant, beckoning, exotic places. For me, at least.
This information has been extracted from the "Official Year Book of the Union of South Africa and of Basutoland, Bechuanaland Protectorate, and Swaziland" (1933-4).
From time to time, auction houses offer Zeppelin covers from the Belgian Congo. The price paid for such items is generally far higher than similar covers from the Netherlands or even Belgium - the reason being that between 1932 and 1939 only 15 flights carried mail originating from the Congo.
The decline of the Portuguese Empire and the rise of Dutch and British mercantile interests in the East led to the isolation and neglect of Portuguese outposts, none more so than Timor.
This article is probably one of the first airmail articles, certainly of any length, to be published in a philatelic journal. It was first published in Stamp Collectors' Fortnightly (January, 1921) from a paper read by Major RS Archer, MC, as his Presidential Address before the Liverpool Junior Philatelic Society, October 11th, 1920.