The remarkable breaks in this singularly great extent of coral reefs, known as the Barrier of Australia, being in direction varying from West to West-North-West generally speaking North-West, leads me to believe that the upheaval by which the base of this huge coral building was formed, partakes of the general north-westerly direction, in which a large portion of the eastern world apparently emerged from the water. A glance at the map of that portion of the globe, will strengthen this hypothesis, placing as it does this singular fact at once before the reader's mind. Starting with the stupendous heights of the Himalaya mountains, and proceeding thence to several groups of the Polynesian islands, New Caledonia, and others, this remarkable similarity in the trend of these portions of the earth is plainly distinguishable. It would appear, therefore, from the general north-westerly tendency of these upheavals, that the cavernous hollows beneath the crust of the earth, within whose bosom originated these remarkable convulsions, have a strong inclination in one direction, a circumstance in connection with the earth's history of great and curious interest. With this general statement of facts, which we note for the benefit of scientific men, and in illustration of the singular changes which are taking place on the surface of the globe, we return to our narrative, from which we have wandered at some considerable length. As the duration of our cruise on the north-west and most interesting portions of the coast, depended in a great measure on the supply of provisions to be obtained at Port Essington, we were naturally anxious to satisfy ourselves upon the point, and accordingly spent but a few hours at Booby Island, taking our departure at 8 P.M. on the day of our arrival. PROCEED TO PORT ESSINGTON. Proceeding towards Port Essington, we experienced a constant current setting between North-West and West, from half to three quarters of a knot an hour, except when crossing the mouth of the Gulf of Carpentaria, when from the indraught its direction was changed to West-South-West. The winds were as Captain King has described them, veering from South-South-East in the morning, to East in the evening, and blowing fresh towards the middle of the day. Beyond this nothing occurred worthy of remark, until the morning of the 17th, when soon after daylight we found ourselves steering rather within a large patch of discoloured water, extending off Cape Croker, the North-East extreme of the Coburg Peninsula, a low point with a slight hummock on it; on the north side of this peninsula is situated Port Essington, thirty miles to the westward of the Cape. CAPE CROKER REEF.