Switzerland. (French Aeronautique Mission in Switzerland). 1917. Stamp-less envelope addressed to France cancelled by 'Republique Francaise/ Mission de L' Aeronautique en Service Industriel' in red on face and reverse, with 'T' hand-stamp bearing French postage dues Yvert 29, 10c brown and Yvert 31, 20c olive (pair) applied and tied on arrival by Poissy date stamp. Rare item of mail from the French Aeronautique Mission in Switzerland.