...hern lakes; and, third, to descend the Mississippi and establish a fortified post at its mouth, thus securing an outlet for the trade of the interior and checking the progress of Spain on the Gulf of Mexico . In pursuance of this plan, we find La Salle and his companions, in January, 1679, dragging their cannon and materials for ship-building around the Falls of Niagara, and laying the keel of a vess...