We launched the second boat, and having loaded both, I left two men in charge of the carts, bullocks and horses, at Bullabalakit, and embarked, at last, on the waters of the Namoi, on a voyage of discovery. IMPEDIMENTS TO THE NAVIGATION. We passed along several reaches without meeting any impediment, but, at length, an accumulation of drift timber and gravel brought us up at a spot where two large trees had fallen across the stream from opposite banks. From the magnitude of these trunks and others which, interwoven with rubbish and buried in gravel, supported them, I anticipated a long delay, but the activity of the whole party was such that a clear passage was opened in less than half an hour. The sailors swam about like frogs, and swimming, divided with a cross-cut saw trees under water. I found I could survey the river as we proceeded by measuring, with a pocket sextant, the angle subtended by the two ends of a twelve feet rod held in the second boat, at the opposite end of each reach, the bearing being observed at the same time. By referring to one of Brewster's tables, the angle formed by the rod of twelve feet, I ascertained thus the length of each reach. This operation occasioned a delay of a few seconds only, just as the last boat arrived in sight of each place of observation. Several black swans floated before us, and they were apparently not much alarmed even at the unwonted sight of boats on the Namoi. The evenness of the banks and reaches, and the depth and stillness of the waters were such that I might have traced the river downwards, at least so far as such facilities continued, had our boats been of a stronger material than canvas. BOAT STAKED, AND SINKS. But dead trees lay almost invisible under water, and at the end of a short reach where I awaited the reappearance of the second boat, we heard suddenly confused shouts, and on making to the shore, and running to the spot, I found that the boat had run foul of a sunken tree and had filled almost immediately. Mr. White had, on the instant, managed to run her ashore, across another sunken trunk, and thus prevented her from going down in deep water opposite to a steep bank. By this disaster our whole stock of tea, sugar, and tobacco, with part of our flour and pork, were immersed in the water, but fortunately all the gunpowder had been stowed in the first boat. THE LEAK PATCHED. This catastrophe furnished another instance of the activity of the sailors; the cargo was got out, and the sunken boat being hauled up, a rent was discovered in the canvas of her larboard bow. This the sailmaker patched with a piece of canvas; a fire was made; tar was melted and applied; the boat was set afloat, reloaded, and again underway in an hour and a half. SHE AGAIN RUNS FOUL OF A LOG.