66 Macquarie Street, Sydney,
25th November 1857.

Dear Sir,

I had the pleasure of receiving your letter of the 16th inst, referring to the proposal of the Philosophical Institute of Victoria to initiate proceedings for the formation of an exploring expedition, having for its object the determination of the character of that portion of the Australian interior which has yet baffled the attempts which have been made to penetrate it.

With reference to the line suggested, simply viewing it on the map, no line could appear better chosen than that proposed, viz- the line of the tropic from E to W. The question, however, is, can this be effected with the means at present available ?

Now, it has been demonstrated that a party, well equipped can perform a journey of equal length with that contemplated; but it is not the number of miles, but the character of the country to be traversed, in which the real difficulty consists, and we should, therefore, inquire what is the probable nature of the country under consideration.

First. The principal tract which is unexplored is comprised between the meridians of 115° and 140° and the parallels of 20° and 32° of latitude, or 1,600 miles. long by 800 miles wide. Its circumference is 4,500 miles, of which only 800 miles (on the NW.) remain unexamined. Along the whole line examined (extending 3,700 miles) the universal character of the country along the boundary is level sandy desert or worthless scrub, without any sign of change in advancing into the interior beyond that of increasing sterility, caused by the greater aridity of the climate, while not one single stream emanates from this inhospitable region, to indicate ranges of hills, better soil or climate, beyond the limits of actual examination.

At what conclusion can we therefore arrive, from a consideration of the premises, except that the interior is equally barren and forbidding with its exterior limits ?

I therefore consider that it is almost hopeless to attempt to traverse this tract of country from east to west, and that the only prospect of success would be to penetrate it in the direction of its shorter diameter (north or south).

But at what point is this practicable? The whole coast of the Australian Bight, from Streaky Bay to Cape Arid, is so barren that neither sufficient water nor grass exist at any spot for the formation of a Depot, from which a party could start, and the result of the expedition from Streaky Bay is very discouraging. Thus it only remains to attempt to penetrate on the northern side. But even here there is scarcely any prospect of success until that coast shall have been settled, when by forming a Depot on the border, or rather on some of the creeks within the limits of the desert, early in the season, light parties might be pushed a considerable distance into it during the short continuance of the rains.

This is certainly a somewhat gloomy view of the subject, but it is, I conceive, our duty to ascertain, as far as possible, the nature, of the difficulties to be met before encountering them, as failure must be the result unless judicious preparations are made to overcome the obstacles which interpose.

Thus reduced to the alternatives of either awaiting the sure but slow development of Australian geography, which must result front a steady adherence to keeping the explorations 400 or 500 miles ahead of the settlements, and gradually reducing the Australian Terra Incognita, or else to resort to the very doubtful, but if successful, more brilliant mode of making energetic endeavours to accomplish the result without delay, prudence would teach us to pause, where undue haste may be disastrous.

Now, as regards the route of any party which might start, under present circumstances, from the east coast, they must of necessity be prepared to return to it, as it is only for a few weeks in each rainy season that they could approach the colony of Western Australia, as it is bounded on the east by a waterless scrub, which has been penetrated at several points some 200 miles; and this tract of country, which perhaps extends as much further into the interior, call only be traversed in the wet when a little water collects on the bare rocks which exist at wide intervals, there being no watercourses, and the lower parts of the valleys occupied by salt marshes and lakes of brine. Even in following the coast to Shark's Bay, I was nearly four days without water while crossing the scrubby plains north of the settlement, and only found one well of water during a search of thirteen days' duration.

Moreton Bay thus becomes the most eligible, point for the organization of an exploring party, and by following down partially the Victoria River of Sir T Mitchell, a good position for a Depot could be selected, from which a lightly equipped party could push to the westward by taking a sweep to the north of Sturt's furthest point.

I expect shortly to visit the country to the NW of Moreton Bay, with a view of searching for traces of Dr Leichhardt and his party, and, if possible, to ascertain the fate of that unfortunate explorer: and should any important features of the country be discovered, a knowledge of which might be of use to the exploring party, I shall feel pleasure in communicating all information relative thereto, as I apprehend that, if the Expedition is undertaken it could not start before the period of my return, as the preliminary arrangements and organisation of the party would occupy several months.

An opinion is prevalent that the range of hills which gives eastern Australia the singular character of large streams descending into a depressed interior, will be found to extend along the north and west coasts. This is not the case, as the mountains range terminates at Cape York, and, except the small tract of hills in South Australia, no ranges exist to the west of the 142° meridian, the whole of the western portion of the continent being only a sandy tableland, the edges of which are serrated by small watercourses which descend its slope to the coast. Thus, in forming an estimate of the difficulties to be in that portion of Australia, we must not adopt any experience of the country within the occupied portion of it. Were the obstacles so insignificant, Australia, ere this, had ceased to be a field for exploration.

In conclusion, I beg to assure you that I shall ever feel a warm interest in whatever may tend to the development of the resources of this continent.

And believe me to remain,
Yours very truly,
A C Gregory.