(Aeronautical) Williams & Young, The Worlds Greatest Aeronauts, beautiful blue illustrated ad showing Balloon with Parachuter below and "The Most Marvelous and Dareing Feat Ever Performed by Humane Being", on unsealed cover bearing 1¢ blue (219), s.e. at bottom, tied by "Chicago" third class grid cancel to the Secretary of Fair in Belleville, Canada at the 1¢ printed matter rate, Very Fine and attractive. Estimate  $300 - 400. $0 (Image)