Los 651
1875, broad overprint 25 c. light-blue, tied by cds. "LUXEMBOURG 25 3 76" to envelope "CONGRES INTERNATIONAL DES AMERCANISTES" with corresponding red official seal on reverse, to Montreal in Canada and re-directed to Chambly Bassin with both arrival marks; the envelope some marginal faults, the stamp in fine condition; a most remarkable and extremely rare official letter, signed Goebel
