Complex sentence: Burt lost interest in it and sold his rights to one Cyrus Spalding for $75 on March 17,1830 with suggested improvements-who ultimately didn't have any further luck in marketing the typewriter.
Split into simpler sentences: Burt lost interest in it and sold his rights to one Cyrus Spalding for $75 on March 17,1830 with suggested improvements. Ultimately he didn't have any further luck in marketing the typewriter.