I have attentively read your letter to the Honourable the Surveyor-General of Western Australia; I have also considered the observations made by you to me, relative to the error you suppose I have fallen into in mistaking the Wizard Peak of Captain King for the hill named by him Mount Fairfax; and I find that I have certainly fallen into this error, a by no means unlikely one, considering the very similar character of the singular group of hills, called Moresby's Flat-topped Range, and the circumstances under which I was journeying. Consequently the country I have described as lying near Mount Fairfax, lies near some other hill to the north of Mount Fairfax, and the country I have described as lying near Wizard Hill lies near Mount Fairfax, being placed from ten to twelve miles south of its true latitude. The mistake arose thus: I carried Captain King's chart, and having only a Kater's compass with me, on recognizing what I considered to be Mount Fairfax, I assumed the latitude of that hill as laid down on the chart to be my true latitude, and made an entry in my journal accordingly. On substituting the name of Mount Fairfax for Wizard Hill, the description of the small portions of the country traversed by us in common, will be found to coincide almost exactly...I am, my dear Sir, yours faithfully, G. GREY. I need scarcely add, that Captain Grey having been obliged to assume his latitude, none of his positions, during this harassing journey, can be expected to be accurate.) MOUTH OF THE GREENOUGH.