CADGWITH, CORNWALL.—On the 6th September the Joseph Armstrong Life-boat went out twice and rescued 40 persons from the Cunard steamer Brest, of Glasgow, which, while on a voyage from Havre to Liverpool with a large number of passengers and a general cargo, went ashore between Cadgwith and the Lizard during a fog. Several shore boats also put off to the vessel and rescued the remainder of the passengers; the crew were saved by means of the ship's boats..