Sale 707 The Knapp Collection of Airmail Flights

1870 (Sep 23), Neptune (Scott BM1), folded letter to Antwerp, Belgium franked with 30c Napoleon Laureate tied by "2" in star with "Paris/ Pl. St. Lazare" c.d.s., Sep 22, and red "PD", backstamped Antwerp Oct 19 (inverted day), Fine to Very Fine.
Maury 1; €15,000 ($15,990).
Scott $10,500.
Estimate $5,000 - 7,500

A rare and desirable cover carried on the first balloon to leave Paris after the establishment of the siege.