Accompanied by Mr. S. Trigg, I proceeded up the river about 180 miles, at which point it ceased to run; we then ascended a hill in the vicinity of 600 or 700 feet elevation above the plain, which I have since found to be, beyond a doubt, Mount Murchison of Austin; unfortunately I was unable to procure a copy of his map or journal, and was thus prevented from laying out my route to the greatest advantage by pushing more to the northward and going over more new ground. As it is, the only information I have been able to gain, beyond completing the plan of the river, is that the principal fall of rain had been eastward of the 116th degree of longitude, and that the tract of country between the great South Bend and Mount Murchison, which proved barely capable of supporting Mr. Austin's small party of horses in November, 1854, is now yielding a pasture nearly equal to the average of the Champion Bay district, and in some parts most luxuriant, the grass having scarcely arrived at maturity was perfectly green; this remarkable change in the character of the country is, I am inclined to think, not entirely confined to this year in particular, but that from meteorological causes this district has not unfrequently the benefit of tropical rains falling during the months of January and February, although not always in sufficient quantity to cause the river to flow as low as the settled districts. It has already been observed by many persons that during the summer months the prevailing sea breezes divide the northerly currents of vapour about 100 miles inland from the west coast, preventing the rain from falling throughout the same parallel of latitude. As near the eastern limits of my route the Murchison throws off two branches nearly equal in magnitude to the main stream, I am induced to imagine that its extreme source does not lie more than sixty or seventy miles beyond that point, and had it not been that I did not feel justified in abstracting so large a portion of time from the regular surveys of this district, there is no doubt but that I could with every facility have completed the exploration of the country as far as the Gascoyne in two or three weeks. On comparing the tracing of the Murchison, which I now enclose, with Mr. Austin's route, it will be observed that there is a difference of seventeen miles in latitude, and something more in longitude throughout the eastern portion, a discrepancy which I am at a loss to account for, as my dead-reckoning to both the outward and inward track agree well with my cross-bearings; my latitudes were, however, taken only with a pocket sextant with a treacle horizon, and might therefore not be implicitly relied on. I have, however, preferred plotting my route exactly as booked in the field, leaving the existing error to be cleared up at some future period. ... From Mr. Trigg, who arrived on Wednesday by the Preston from Champion Bay, we have gathered the following additional particulars:--