Wm.W. Hubbell attorney and counsellor at law, Philadelphia, informs us that he has perfected an invention for a new method of propelling steamships, which he states is more efiicient and constant in its propulsive principle than side wheels or propeller screws. He has shown it and discussed its merits with some able marine engineers, who have agreed that for war steamers it will surpass anything now on the ocean for speed, constancy of ac-bion and invincibility. The rudder and every nast may be shot away, yet the ship will not be deprived of its speed or management. He intends to take out patents in foreign countries as well as for home. The improvements may be expected to be fully illustrated and described in our columns when the inventor returns from the south (where he has gone on business), during some part of next month.