Adelaide is a little south of Sydney in latitude, and Oodnadatta 20 a little south of Brisbane, yet what a difference between the two parallel journeys by rail! The explanation is to be found in the rainfall figures: north of Port Augusta we enter the zone where the annual amount is under ten inches. The railway reminds us of those starting from the east coast and ending at some remote point in the interior; but there seems very little country here for our line to exploit or develop. To understand fully its meaning we must look back at the past history of the region. South Australia was founded by an Association formed in England with the object of building up a model agricultural colony. The plan was to sell the unoccupied land and use the proceeds to aid suitable emigrants in settling there. With this idea Adelaide was founded in 1836. For a few years the colony was poor, as it was intended to be self-supporting and the capital in private hands was insufficient to develop the country. But progress was helped by the various discoveries of copper, from 1842 onwards, at Kapunda, Burra and other places; and by 1855 the colony was able to export large quantities of agricultural produce to the other colonies, which had depended mainly on Tasmania up to this time. It is curious that the State which is still mainly agricultural was the first to develop its minerals on a large scale; but as the mineral was copper and not gold, it led to no rush of settlers, but only to a steady growth of population. The older mines have been long worked out, but those in Yorke Peninsula and in the Flinders Range still produce large quantities. Here are 21 views of the Wallaroo and Moonta mines in the Peninsula. 22 With the exception of some iron ore, which is not much worked, South Australia has no other important minerals of its own: yet at Port Pirie, on the east side of Spencer Gulf, we find large smelting works. To explain this we must look back again at the railway map. From the port a line runs north-east for two hundred miles or more, to the Silverton country, just inside the New South Wales border which we have already visited. It is the natural outlet for this district, as Sydney is more than twice as far away. Here we see Port Pirie and some of the smelting works. The works 23 also handle iron ore which is brought down to the opposite shore 24 of the Gulf by a short railway from Iron Knob, near Lake Gilles, in the dry interior of the western plateau. In the case of this district we notice once again that the artificial boundary following a line of longitude has no correspondence with the natural features of the country.