Here was the question:What is wrong here (from a book on 18th-century medicine)? "Not only could hospital surgeons earn fees from teaching apprentices and house pupils; their private practice benefited from their leap in status."
Congratulations to 60% of you. The semicolon in the middle of the sentence should be a comma. One use of semicolons is to separate two complete sentences, but the "not only" part is not a sentence.