The observations were made at the South-East point of Quail Island, which by them is placed in latitude 12 degrees 30 9/10 minutes South, and longitude 1 degree 42 1/4 minutes West of Port Essington. The almost insulated character of this part of the coast, and the quantity of soundings the openings required detained us until the 6th of October, when we passed out on the western side of the large reef in the centre of the entrance, which is the proper one, and received the name of West Channel. The western entrance point of Bynoe's Harbour, bearing South 15 degrees East, leads through it. This guide is only, however, of service to a certain distance within the entrance, as it leads over a small patch that dries at low-water, distant two and a half miles from the above-mentioned point on the same bearing. To avoid this danger, it is therefore necessary to haul over towards Quail Island, when the highest hummock on it bears South-West 1/2 West. The tides follow the direction of the channel, varying in velocity from one to two knots. The ebb in the offing set West-North-West. PORT PATTERSON. The reader will be able to have an idea of the large sheet of water these united harbours form, by knowing that Port Patterson is twelve miles long and seven wide at the entrance; though at the upper part, forming the mouth of Bynoe Harbour, it is not half that width. The latter winds round to the South-East for a distance of 15 miles, with an average width of two, and a depth of nine fathoms. Thus terminated our exploration in this neighbourhood; the result having been to give this part of the coast quite an insulated character. The sheets of water creating this new feature, although monotonous with their mangrove-lined shores, still conveyed us many miles into various parts of the continent that had never before been seen by a civilized being. Another opening of far greater magnitude, and promising in all probability to lead far into the interior now lay before us, at a distance of 140 miles further on the coast to the south-west. By the evening we had lost sight of the land near Port Patterson, and were steering towards the opening that promised so much. A gap in the coastline, 28 miles wide, with a strong tide passing to and fro, failed not to give birth to endless speculation as we approached the spot. I had always looked forward to the examination of this unexplored portion of the North-west coast, as one of the most interesting parts of our survey. REACH POINT PEARCE.