Some of the new ferry boats running be tween our city and Brooklyn, are well venti lated ; the old boats are defective in this es sential particular; and the Williamsburgh boats, when the cabins are crowded, are no better than the Black Hole of Calcutta. Pure air is as essential to health as pure water : no person would drink out of the gutter; but who is so dainty respecting the atmosphere, of which he must drink continually ? Some of the boat cabins for gentlemen (wrongly named) are converted into smoke houses, to tally unfit for decent men or beasts.