September 1st.--To-day we leave the Rock Ferry Hotel, where we have spent nearly four weeks. It is a comfortable place, and we have had a good table and have been kindly treated. We occupied a large parlor, extending through the whole breadth of the house, with a bow-window, looking towards Liverpool, and adown the intervening river, and to Birkenhead, on the hither side. The river would be a pleasanter object, if it were blue and transparent, instead of such a mud-puddly hue; also, if it were always full to its brim; whereas it generally presents a margin, and sometimes a very broad one, of glistening mud, with here and there a small vessel aground on it.