THE TOWER BRIDGE.

Temuka Leader, Issue 2705, 30 August 1894, Page 3

THE TOWER BRIDGE.

The Tower bridge, which was opened i by the Prince of Wales on June 30, is considered alike a triumph of the architect’s art and the engineer’s skill. The designs, by the late sir Horace Jones, were perfected and realised by Mr Wolfe Barry. The bridge spans the Thames immediately below the Tower of London. It is on the “ bascule” principle, with two Gothic towers, the centre span of 200 ft being cut in halves to be raised and brought flush with the. towers by machinery concealed within the latter. There is an upper footway for passengers for use when the bridge is open and approached by staircases or lifts within the towers. Horse and waggon traffic must stop till the bascules are down. The bascules work on a great pin'or pivot. One leg of the bascule is 100 ft long from the edge of the pier—more from the pin. The other leg, concealed inside the pier, is much shorter, so it is helped by having 290 tons of lead ballast fixed on at the end. Above this short leg is fixed a quadrant or. quarter circle, with teeth on the curve of it which play into the teeth of a fixed wheel by which power is applied to raise the bascule. That means, of course, raising the long leg and depressing the short one, which has a circular course scooped out for it to sink in somewhere in the bowels of the pier. fixed wheel being turned by the engines in the direction in which the hands of a clock move, causes the toothed curve of the quadrant to work its way downwards, carrying the short leg with it and cocking the long leg up until instead of lying along horizontally it stands straight back against the tower; to join the low level bridge up again the the process is reversed, The pin or pivot of the whole affair is a 21in steel bar, and it bears 1000 tons; the bascules each weigh 950 tons. When the bridge is dosed there is sufficient height at high water for the ordinary river traffic. The approach roads and land spans (which are on the suspension principle) are 60ft wide, and the central span 50ft wide. The two immense piers in the bed of the river are described as the largest in the world. The total coat of the bridge and machinery will be, from first to last, about f 1,000,000 sterling. The total length of the bridge and approaches is about half-a-mile. About 31,000,000 bricks, 19,600 tons of cement, 70,500 cubic yards of concrete, 15,000 tons of iron and steel, and 2,000,000 rivets have been utilised. Two sets of hydraulic engines are connected with each pier, working four hydraulic lifts, two to each pier, which will accommodate from 20 to 25 passengers, and the journey will occupy about a minute and a-half. The opening, passage of the vessel, and closing will occupy only four or five minutes. The towers of massive steel frames, in,.storeys covered with masonry, are 264 ft high from the foundations, or 200 ft high from the top of the piers, and they contain the lifts and rooms for the working staff. From 500 to 800 men were generally at work on the structure, while seven have been killed—about one a year.