The bay into which it flows, named after Sir Charles Adam, is six miles deep and ten broad at the entrance, where there are 9 fathoms. The shores gradually approach each other, and at the head, where it receives the waters of the Adelaide, the width is only one mile.
The mouth of the river is fronted with shoals that extend out five miles; the channel between them is narrow, 3 and 4 fathoms deep, and lies on the western side of the bay. A guide for the mouth of it is the east entrance point of the river, bearing South 40 degrees East.
The generally discoloured state of the water prevents the shoals from being seen, as well as the coral reefs extending from half to three quarters of a mile off the east side of the bay, where there is excellent anchorage. Sea and land breezes prevailed; the former blowing from the North-West which gave it the advantage of being of easy access either from the westward through Clarence Strait, or from the eastward through that of Dundas. The spring tides sometimes rise 18 feet, when the time of high-water is six o'clock. The stream set North-East and North-West from half to one knot, changing to the latter direction two and a half hours after high-water. Our observations place Escape Cliffs (too remarkable and conspicuous to be overlooked, and which ships should anchor abreast of) in latitude 12 degrees 8 1/2 minutes South and longitude 0 degrees 15 minutes West of Port Essington. The variation of the compass was 2 degrees easterly. I was able at this anchorage, by a bearing of a distant point, to ascertain the local attraction in the ship, which in no instance exceeded 1 degree, being the amount we had found at Plymouth, previous to our departure from England. Our deeply interesting researches on the south side of Clarence Strait, leading to so important a discovery, were now concluded.
EXAMINE MELVILLE ISLAND.
The success which had rewarded our efforts, made us wish to cling to the spot, and it was therefore almost with regret that we found ourselves leaving to examine the southern shores of Melville Island, where we anchored two miles from the beach, and fifteen within the west entrance of the strait. A quarter of a mile off the sandy flat, extending some distance from the shore, there was one fathom of water, being a very gradual decrease from six where the ship lay.
The necessary angles and bearings for the survey, were taken from the top of some cliffs sixty feet high, composed of a red sand and ironstone, and a white kind of marl or pipe clay. The shore trended nearly South-West and North-East. Six miles in the former direction is an inlet which Mr. Fitzmaurice has visited from the Vernon Isles, and another much smaller, about a third of the intervening distance from where we stood. The high land which was almost level, lay about three miles in our rear, following the trend of the shore. Two peaks rising in hollows on it attained an elevation of 260 and 290 feet. There were no rocky points visible at low-water--a clean sandy beach, which appeared, strange to say, to have been washed occasionally by a heavy surf, forming the coastline. A singular clump of Casuarina was close to the westward of the cliffs, and its dark naked aspect contrasted with the stunted gumtrees and scattered palms, sparingly sprinkled over this sterile tract of country. With the exception of a few seabirds, there was nothing living stirring to change the opinion we have just expressed of this part of Melville Island. Our visit, however, was not to be forgotten in an instant, although no very pleasing recollections were connected with it.
GREEN ANTS.
Whilst taking a few angles near the cliffs, we suddenly experienced a series of severe bites or nippings in several parts of our body, and looking round to discover whence arose this unexpected attack, found ourselves under a tree covered with large green ants. Their bites were exceedingly painful, and it was only by beating and tearing off our clothes that we could rid ourselves of these unwelcome visitors. From a distance our appearance must have been sufficiently amusing. One moment soberly intent upon our duties, and the next jumping like madmen, and hastily stripping off our garments. The name of Ant Cliffs records our visit to the south shores of Melville Island. The tide on this side of the strait ran nearly two knots an hour, following the direction of the shore; the time of high-water being a quarter of an hour earlier than in Adam Bay.
August 15.
Recrossed Clarence Strait to obtain observations for rating the chronometers, and examine the extensive shoal off Cape Hotham. On anchoring near its edge, a patch with only five feet was discovered close to the ship; the muddy and restless state of the water, caused by a meeting of the tides, setting out of Van Diemen's Gulf and Adam Bay, renders it necessary to approach Cape Hotham from the northward, with caution. However, the unusually great depth, for this strait, of twenty fathoms, will give warning of a ship's proximity to this danger, the limits of which have been given on the occasion of our first visit to Cape Hotham.