Mr. Govett was afterwards employed by me to make a detailed survey of the various ramifications of these ravines by tracing each in succession from the general line of road; and thus by a patient survey of the whole he ascertained at length the ridge connected with Mount Hay, and was the first to ascend it. Guided by Mr. Govett I was thus enabled to place my theodolite on that summit. I found the scenery immediately around it very wild, consisting of stupendous perpendicular cliffs, 3000 feet deep, at the foot of which the silvery line of the Grose meanders through a green valley into which neither the colonists nor their cattle have yet penetrated. Having looked into this valley from the summit of Tomah also in 1827, I was tempted soon after to endeavour to explore it by ascending the river from its junction with the Hawkesbury near Richmond; but I had not proceeded far in this attempt, accompanied by Major Lockyer and Mr. Dixon, when we were compelled to leave our horses and, soon after, to scramble on our hands and feet until, at length, even our quadrumanous progress was arrested in the bed of the river by round boulders which were as large as houses, and over or between which we found it impossible to proceed. INTENDED TUNNEL. The object which I had then in view, with the concurrence of the Governor, was to carry the western road along the valley of the Grose, and by cutting a tunnel of about a mile through a ridge at the head of it, to reach the vale of Clywd, and so avoid the mountains altogether. The ascent to them from Emu, and the descent from them at Mount York, were both then extremely bad; so much so indeed, at the latter pass especially, that a grant of land was publicly offered by the Government to whoever could point out a better. Both these obstacles have since been overcome. PASS OF MOUNT VICTORIA. The pass of Mount Victoria, named by me after the youthful Princess and opened by Governor Bourke in 1832, descends at an inclination of 1 in 15 (where steepest) and avoids the abrupt descent by Mount York. ADVANTAGES OF CONVICT LABOUR. The new road from Emu plains, which is still less inclined, has been made during the government of Sir Richard Bourke, and relieves the Bathurst teams from the difficulties of Lapstone hill, the ascent of which cost them a whole day. The value of convict labour to a young colony is apparent in these new passes, cut in many places out of the solid rock; and this advantage will be permanently recorded in these works and others now going forward in different parts of this mountain road, which must finally make it one of the best in the colony. COUNTRY OF MULGOEY. The difference between the lower country on the Hawkesbury and the region which I have endeavoured to describe is very striking. The rocks are also different, for on the side of Cumberland they consist of trap, and on the other or that of the mountains, of sandstone. EMU PLAINS.