Page:ChroniclesofEarlyMelbournevol.2.pdf/33

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THE CHRONICLES OF EARLY MELBOURNE
513

"The City Council insisted on each of the large columns consisting of a single stone. The stones were easily obtained in the quarry, but the task of conveying them to the work was more difficult. The bridges and culverts between the quarry and the Castlemaine Station were most carefully examined, and very elaborate preparations made and precautions taken. The large blocks were packed upon heavy waggons drawn by twenty-four horses, and were landed without serious accident on four large trucks which had been specially strengthened and prepared. A special train was formed, and run at a slow speed at a time when all other traffic could be conveniently stopped. On arrival at the site of the work, a twenty-ton crane was ready to unload the huge stones, and special machinery was employed to polish them. None of the granite-polishing firms in the colonies had the necessary plant for working these columns. The contractor was, therefore, compelled to construct his own, and many ingenious contrivances had to be originated to overcome the unusual difficulties. It is stated that so large a surface was never before polished at one time. By means of the powerful plant available these stones were allfixedin position with little difficulty, and without any casualty. This plant consisted of three Goliath travelling cranes, of 45ft. span, and capable of lifting twenty tons and travelling on a high staging side by side the whole length of the bridge works.

"The iron for the bridge was specially rolled, and workshops were erected at South Melbourne for the construction of the girders for this and the 'Falls' Railway Bridge. There are altogether 1,000 tons of wrought iron in the bridge—the iron for the rivets of which, if placed on end would reach thirty miles—and about 200 tons of cast iron.

"A somewhat detailed description of the new bridge will doubtless be interesting. The bridge consists of three spans of 100ft. each, and a land span of 24ft. at the south end, and measures in all over abutments about 400ft. in length. The width between the parapets is 99ft., 63ft. being occupied by the tramway, carriage-way, and side channels, leaving a footpath 18ft. wide along each side. The abutments, piers, and wing walls are built of bluestone, with concrete foundations resting on solid rock. The three main or river spans of the bridge are in the form of segmental arches, having a rise of 10ft. at the crown, each arch being formed of 10 ribs constructed of plate and angle iron, and having a depth of 3ft. at the springing and 2ft. 6in. at the crown. The top boom, spandril, filling, and bracing, consist of angle T and plate iron. Over the longitudinal ribs transverse plate-iron girders, 12m. in depth, are placed, spaced generally about 5ft. 3m. apart. These girders, in the case of the roadway, carry the bent plates which form the constructional part of the floor of the bridge. In the case of the footpaths, longitudinal rolled iron bearers are introduced over the cross girders, with the object of gaining the additional height required, and the floor-plate sare secured thereto. The main longtitudinal ribs to the land span of the bridge are straight wrought-iron plate girders, the cross girders and super-structure being of the same construction here as the river spans. Over the bent floor-plate, concrete is filled in, brought to a regular surface, and finished with a 1 in. layer of cement mortar. Over this the tram and carriage-ways are laid with red gum blocks, and the footways formed of Seyssel asphalt with a kerbing of bluestone. After the design for the bridge had been adopted, special provision had to be made for the accommodation of the cable tramway, which necessitated the lifting of the roadway to the extent of 5ft. 2in., and the parapets were increased in height from 3ft. 3in. to 3ft. 9in. The face-work to the arches and girders of the bridge, also to the spandrils and the parapets over the openings, as well as over the wing-walls, are of cast-iron. The caps and parapets over the abutments, piers, and pilasters to the wing-walls are of stone, with carved enrichments, harmonizing with the cast iron work. The south approach to the bridge is carried over an embankment, which is more than 30ft. in height at the highest point. The original width of the river at the site of the bridge at ordinary times was about 130ft. It has now been increased to about 316ft."

Richmond Bridge.

The floods used to pummel the shaky old punts in which Dr. Palmer speculated at Richmond, and two of them having gone off on an excursion towards the end of 1849,a company was started for the erection of a bridge there in February, 1850, with a capital of £3000, in 300 £10 shares. A Provisional