Engineering Wonders of the World
Volume I

92 ENGINEERING WONDERS OF THE WORLD. MAP SHOWING SITE OF BRIDGE. wards to 400 feet at water- level. On the north bank the cliff is practically sheer, while the southern face has a shelf about half-way up, and is generally more easy of access. The design of the bridge was entrusted to Mr. G. A. Hobson, a member of the firm of Sir Douglas Fox and Partners — a firm that has been prominently connected with engineering enterprise in Rhodesia and other parts of South Africa. The plans finally chosen were for a two-hinged span- drel-braced arch bridge. The words “ two-hinged ” imply that allow- ances for A Description movements , of the due to alter- Bridge ations in temperature and load are concentrated on the points of support at the bottom of the end posts? Spandrel- bracing makes the horizontal top chord, over which the track is laid, the partner of the curved arch in the matter of bearing the strains and stresses to which an The Site chosen. cataract, and inside the zone in which spray falls for several months of the year, so that the wish of Mr. Rhodes that the trains should catch the spray as they passed has been fulfilled, though the author unhappily did not live to see its of the wish fulfilment. At the point chosen the chasm has a top width of about 750 feet, and narrows down- arch bridge is subjected, and also affords certain advantages in the erection of the members. It should be mentioned that the bridge has, in addition to the main arch, two short end spans of 62 j and 871 feet respectively, sup- ported by the banks and the end posts of the arch. The arch itself is 500 feet long between the centres of the end posts, which are 105 feet high. The rise of the crown is 90 feet, so