Airgraphs
These were special letter forms used by Great Britain during World War 2 for forces mail from overseas locations.
To save space letters were written on special forms and microfilmed. The microfilm was then flown to or from Britain, processed and photocopies made of the original transcription. These photocopies were then placed inside window envelopes and delivered in the normal way. Airgraphs stopped at the end of the war.
There was an historic parallel in this idea with events that had happened in Paris 70 years earlier.
During the siege of Paris in the Franco-Prussian war, (1870 - 1871), messages were sent from the city by balloon. To save space on the balloon, letter were reduced photographicially, and the primitive microfilm was sent instead of the originals. At Borbeaux, the headquarters of the then French goverment, the films were mounted onto glass slides and projected onto screens. From here clerks copied these messages and they were then posted in the normal manner.
The situation with airgraphs was designed to save space and weight on the aircraft which were carrying the mail. Towards the end of the war air letter sheets were used for the same weight saving reasons. These sheets were printed on special thin light weight paper and were charged at a reduced rate. As well as those introduced by Britain, the United States also used air letter sheets for mail being sent to prisioners of war who were held in occupied countries. This mail was carried at the reduced rate of 6 cents.
