Steamschip "American" Aground. The Dutch tank steamship American, Capt. Voege, loaded with petroleum for Antwerp, grounded on the shoals off Robbin's Reef lighthouse yesterday afternoon. The vessel was still aground at midnight, but lying in an easy positlon. It is expected that she will get off at high water this morning. The vessel is a new steamship. She measures 2.927 tons.