Exciting account by Clyde Tombaugh of the hours leading up to his discovery of Pluto. Typed 8.5'' x 11'' document signed ''Clyde W. Tombaugh / 26 Nov. 1990'' reads in part, ''...In February 1930, after struggling through 'Taurus' I skipped [to] eastern Gemini where the stars were less thickly packed. I suddenly spied an object 'That's it!' I exclaimed to myself. Any possibility of the phenomenon being a pair of variable stars was now ruled out. This seemed to be it...'' Tombaugh crosses out an errant ''a'' in description. Near fine condition.