I love the heavy and complex style of H.P. Lovecraft, but lately I have noticed a lot of odd choices in his punctuation while reading through The Case of Charles Dexter Ward. In one example, I cannot find any rules concerning his comma usage: "At the end of the conference he was very grave, and enjoined strict silence upon the younger men." What rules make that sentence correct, if any? Moreover, are there any rules that are used to place a comma with a conjuction between an indepedent clause and a dependent clause?