A GREAT ENGINEERING WORK.

New Zealand Tablet, Volume VI, Issue 269, 28 June 1878, Page 17

A GREAT ENGINEERING WORK.

A bridge of such proportions as the world has never yet seen is proposed by Sir Joseph Bazalgette for the purpose of connecting the two banks of the- Thames in the vicinity of the Tower, and the plan has received the approval of the Metropolitan Board. The operation contemplated by the Board consists in building up a structure of steel crossing the Thames in one tremendous span, clearing the water at such an altitude that three-fourths of the masted ships which require to do so will be able to pass under the elevated roadway without any hindrance, While the remaining fourth will merely have to lowci their topmasts, w*hich they may very well afford to do, as topsails are not carried in the Thames above Graveseud. She' case now before us affords a striking instance of the great pracKal results which ate apt to follow from improved processes in the arts. Steel, when perfect in its composition, is capable of bearing a much more severe stiain than iron, but the difficulty has been to insure uniformity of quality in the superior metal. Sir J. Bazelgette observes that, until a recent date, the costliness of steel and the uncertainty as to its quality have prevented its use in large structural ■works. But the improvements which have been effected by Dr. Siemens and others in the manufacture of this metal have rendered it more thoroughly trustworthy, and have enabled it to be produced, at a moderate cost, with nearly double the strength of iron. Hence it is now possible to construct such a bridge as would have been practically out of the question a few years ago. One bold span of eight hundred and fifty feet will carry the proposed highway across the river from the Irongate stairs to Horselydown. Of course the approaches extend farther inland The bridge is designed in the form of an immense span, and is composed of two immense girders, tlie arch springing from the foot of that which appears to bo a flanking tower on each side of the river. The roadway passes almost in. a level line very near the top of these towers, and intersects the aich at a short distance from the shore, the greater part of the roadway being suspended from the parallel girders hptwecn which it passes. The design is, in fact, a simple one, and if it does not strike the eye at once as possessing any degree of elegance, it cannot be called altogether ugly. — London Standard.