From observations made on the rains and winds in Western Australia, and careful inquiries on the same subjects when I was in South Australia, and on a comparison of the two, I am inclined to believe that the climates of the two colonies assimilate. A wet winter in one is a wet winter in the other. Both receive their rains when the wind blows from the north-west to south-west. Thus the rains from South Australia pass from the Indian Ocean over Western Australia, and the whole island, to South Australia. The hot wind of Western Australia blows from the north-east; and, in fact, the hot wind of both colonies comes from the same portion of the great island. That which is the hot wind in summer in Western Australia is the cold wind in winter; and the same in South Australia. The reason is obvious. It is evident, from the fact that South Australia receives its rain from the Indian Ocean, that there are no mountains in the interior of sufficient elevation to intercept the clouds; that there are no mountains in the interior, is shown also by the absence of rivers emptying themselves into the ocean. From the observation of Mr. Lefroy and myself, we were led to suppose that the interior consisted for the most part of immense clay plains; the lower portion of these plains being hollowed into the large shallow lakes we meet with in our journey. Where the country is a little more elevated the plains are sand instead of clay. In winter these plains are covered with water, as the drifted leaves on the bushes testify; and the marks of water on the surface are very evident. Now, when the winter winds pass over these immense masses of water, the great evaporation renders them intensely cold; and they arrive in the colony laden, (if I may so unphilosophically express it,) with cold, caused by rapid evaporation. In summer these very plains are equally the cause of the hot wind; for when the rains cease, and the sun acquires his summer power, the water is quickly evaporated, the clay becomes baked, and the heat is reflected from the hard heated surface quite sufficiently to raise a thermometer to 110 degrees in the shade. The wind is now driven towards the colony laden with heat from the cracked, baked, clay-plains in the interior; and thus it is, that at different seasons the same country produces such opposite effects. But although the general state of the interior is barren and unproductive, as I imagine, I do not suppose that it is entirely so. I believe there are many cases of good pasture land in the midst of this sterile country; fertile spots, small when compared with the vast area of indifferent country around them, but large in themselves. And these pastoral oases are more cultivated than the worthless land amid which they are placed. In these patches of good land there are always water-holes to be found, and water-courses well marked, conducting the surplus waters to the lakes in the clay plains.