GENERAL OBSERVATIONS.

It may be proper to conclude our account of Houtman’s Abrolhos with a few general remarks.  They form three groups instead of one, as was formerly supposed; Pelsart Group being separated from Easter Group by a channel, the least width of which is four miles, whilst the middle passage between the latter and the Northern Group is six miles wide.  The Abrolhos extend in a North-North-West direction forty-eight miles, diminishing in breadth towards the north; the greatest width of Easter and Pelsart Groups being twelve miles in a West-South-West direction.  In Easter Group the outer reefs are most distant from the islands, being there four miles from the nearest, which is Rat Island.  In the Northern Group the islands are more detached than in the others, and North Island is separated from them by a distance of ten miles.

We have already alluded to the regularity and sameness in the soundings in these groups, and between them and the main, clearly showing that they are not connected with each other, but rest on the outer extremity of a level or bank, stretching out from the main, and having a slight southerly inclination, the depth (29 fathoms) between the southern group and the coast being greater by four fathoms than between the coast and the northern group.  On either side of the Abrolhos, at the same distance from land, the depth is more than 100 fathoms.  The general nature of the bottom, in the quiet places between the reefs, is a fine grey sandy mud or marl, but in more exposed situations this is not so compact, whilst broken shells are more abundant.  This bottom bears a striking resemblance to that within the Great Barrier Reefs.

After leaving the Abrolhos, as I have narrated, our progress to the northward was unusually slow, and between the parallels of 26 degrees 50 minutes South and 25 degrees 40 minutes South we again got into soundings varying from 187 to 81 fathoms, fine grey sand.  At the greatest depth the ship was forty miles from the land, and twenty miles at the least, which was off Dirk Hartog’s Island, at the south point of Sharks Bay.  In passing round the north-west extremity of the continent we delayed, again endeavouring to get sight of Ritchie’s Reef; but, on this occasion, as on our passage from the Victoria to Swan River, it was not seen, and as no bottom was obtained with 200 and 240 fathoms in its assigned position on the chart, it must either have a very different one or does not exist.

PROCEED TO THE COAST.

The part of the North-west coast that had not been seen by Captain King, commencing a short distance to the east of Depuch Island, it was resolved that our survey of that part should begin there, and on the 9th of June the Beagle reached an anchorage off a sandy bay on the north-east side of that island.  As we drew near our progress was impeded by a fierce south-east breeze during the forenoons, which we found to prevail during our stay, being stronger at the full and change of the moon.  Although coming directly from the land they quite made us shiver, reducing the temperature on one occasion to 59 degrees.  These winds began about daylight at south, gradually veering and drawing round to the eastward as the day advanced, and subsiding again as rapidly after noon, leaving the evening and night generally calm.