1920 (Oct. 6) First Air Service Dispatch cover with special cachet ds of Cristobal and 2c ovpt. tied at Balboa (Oct. 4), special boxed 6-line cachet « Aviator Encountered Impossible Weather Conditions Nearing Jamaica, Compelling Return. Mail Re-dispatched by Steamer, » addressed to John Luff of Scott’s, truly scarce, very fine (Mü. 2, 10’000pts)