Issue 5

The new opening bridge over the River Cart at Inchinnan, near Renfrew, carries the principal road from Glasgow to Greenock and other west-coast ports, and is the only bridge over the Cart between Paisley and the Clyde, a distance of 3 miles. It provides an improved and widened navigation channel between Paisley and the River Clyde. The earliest attempt to improve the Cart navigation was made in 1753. The Cart Navigation Trust was formed in 1834, when the present swing bridge was erected over an artificial channel. The financial embarrassments of the Trust led to the undertaking becoming derelict in 1915. In 1920 power was granted to the Burgh of Paisley to improve the navigation-channel at Inchinnan and to replace the old swing bridge by a modern opening bridge. The widened channel has a clear width of 90 ft. and a depth of 21 ft. at high water length of about 250 ft. William Bertram Hall

l. From the standpoint of purely theoretical design all the members in a framed structure should be made of such dimensions that their material will be stressed to the allowable limit under the external load system considered, since a structure proportioned in this way will ensure maximum economy in the use of material. In many cases such an ideal structure may be impracticable, and will have to be modified to meet a variety of conditions imposed byconsiderations other than those of theoretical design. Whatever modifications are necessary, however, to meet such conditions the ideal design will have considerable value as a basis for the development of the final scheme embodying the requirements of practical engineering. In some cases, e.g., in the design of all aircraft structures, the reduction of weight is such an important consideration that very little is permitted to stand in the way of its attainment, and in such cases this ideal structure would be very closely followed. Professor A.J. Sutton Pippard