The conditions prevailing also compelled each span to be completed near the bank upon a pontoon, the steel-work being supported upon a heavy scaffolding. The pontoon was somewhat shorter than the span of steel which projected an equal distance over either end of the former. When all was ready, and when the tide was approaching its highest point, the pontoon, with its ungainly load, was towed and was warped gently between two adjacent piers, in such a way that the ends of the span were brought into their relative positions upon the masonry. The pontoon was then made fast, and the actual settling of the steel-work was left to the movement of the tide. As the river fell, carrying the pontoon with it, the span descended until in due course the ends rested on the masonry. The water still falling, the scaffolding presently dropped below the steel-work, leaving the latter clear in position. Finally, when the tide had fallen still more, the pontoon was cast off and drawn away, leaving the two piers connected by the steel. Such methods demand extreme care, unerring judgment, and a readiness to meet any emergency on the part of the engineers. The American bridge-builders who carried out this undertaking had several exciting incidents. The most thrilling and anxious was when one of the pontoons got out of control with its precious freight and became stranded on the bank, where it had to remain in a dangerous listing condition until the tide rose again, to enable it to be floated off and towed to its destination. In comparison with the New South Wales railways, the lines of the other States lack outstanding features, yet their work has been attended with peculiar difficulties. In South Australia, where settlement has not proceeded so rapidly as in the adjacent State, the policy is to build the lines with the minimum of cost to meet the demands for cheap railways to connect communities scattered over a large area. That this is a remunerative practice is borne out by results. Although the wide gauge of 5 feet 3 inches is adopted on what may be called the trunk lines extending from Adelaide to the eastern border, to effect junction with the Victorian railways, thereby securing through railway communication between Adelaide and Melbourne without change of carriage, the greater part of the railway system is the narrow gauge of 3½ feet. The railway thus acts as a pioneering campaigner in the fullest sense of the word, and in this way it has been possible to push the iron road towards the heart of the rich inland country so far as Oodnadatta. Queensland is practising the same principle, three lines having been forced slowly towards the eastern boundary of that State in three roughly parallel lines from three different points on the coast--though the latter in turn are connected. In due course the inland ends of these lines will be joined up, and there will be a complete circle from which spurs can be driven to meet development.