In 1921 an Air Mail Service was established between Egypt and 'Iraq by means of regular service flights undertaken by ma chines of the Royal Air Force, but in 1927 was transferred to Imperial Airways. The saving of time effected was very great, as the short transit of 85o miles across the Desert cut out the long sea journey from Egypt to Bombay and from Bombay to the Persian Gulf. In March 1929, however, this service was super seded by a through Air Mail between London and Karachi by way of Italy, Greece, Egypt and 'Iraq. This is longest regular through Air Service in existence, and the time occupied from Lon don to Karachi is 71 days as compared with 14i by ordinary mail from London to Bombay. The London-Karachi service will in the immediate future be extended by the creation of air services in and across India under the auspices of the Indian Government. Another recent development of considerable postal value is the French service to Brazil and the Argentine via Morocco and Dakar.
The experience of air mail services since 1919 has been suffi cient to enable certain definite conclusions to be drawn. In the first place, for short distances, such as London–Paris or London– Amsterdam, the existing means of communication are so good that the amount of traffic attracted to an air mail is and must re main exceedingly small. When, however, the services cover greater distances and the high speed of the aeroplane can thus offer a definite and tangible advantage, the possibilities of attracting traffic are considerably greater ; if and when the difficulties of night flying are successfully overcome, and it is possible for letters posted in the evening in London to be delivered next morning in Berlin, Vienna, Milan, Berne, or Copenhagen, the European air mail will offer advantages which it will be impossible to ignore.
In the second place, the air mail will, so far as can be foreseen, remain definitely as a luxury service. The capacity aeroplanes, and even of the largest airship at present in contemplation, is only adequate to convey a fraction of the mails available; and the cost of air transport is very substantially in excess of that of transit by railway and steamship.
The importance of air mails from the international standpoint was recognized at an early stage by the postal administrations of the world, and provision was made to include them in the general Postal Convention signed at Madrid in 1920. The relative pro visions were amplified at the later congress of Stockholm in but their rapid development has resulted in the calling of a special International Air Mail Conference in 1927, at which a definite code of regulations to be applied between the signatories was de vised as a preliminary step to an expansion of the provisions of the Postal Convention. Considerable progress was made in the direction of standardizing rates of air postage, and of unifying practice generally. It is worthy of remark that in accordance with postal tradition, complete liberty of transit is established for air mails ; i.e., every country which establishes an air mail gives to every other country the fullest facilities for despatching its own mails by it, on the payment of certain definite and uniform charges. The result is that the latest developments in aviation are placed at the disposal of the public of all countries, and new air lines, wherever established, are available without restriction for the development of international communication.