French engineer (1841–1925) best known for his pioneering work in aviation. Very rare ALS in French, signed “Ct Ader,” one page, 5.25 x 8, Chateau de Ribonnet letterhead, December 9, 1920. Letter to Jacques Mortane an early champion of aviation, who wrote about Ader. In part: “I hope you have recovered your health and can resume your activity at ‘La vie au Grand Air.’” In very good condition, with paper loss to top left, scattered soiling, small mounting remnant to lower right, adhesive to right edge, and a musty odor. Ader had reportedly flown 50 meters as early as 1890, more than a decade earlier then the Wright brothers. RRAuction COA.
