Complex sentence: Cornelius would operate two of the earliest photographic studios in America between 1839 and 1843, but as the popularity of photography grew and more photographers opened studios, Cornelius either lost interest or realized that he could make more money at the family gas and lighting company.
Split into simpler sentences: Cornelius would operate two of the earliest photographic studios in America between 1839 and 1843. As the popularity of photography grew and more photographers opened studios, Cornelius either lost interest or realized that he could make more money at the family gas and lighting company.