upper-chord eyebars and adjustable verticals, by means of which one half of the central span is cantilevered over the stream to meet the other half, after which the toggles are to be removed. This method of erection can be understood by reference to the diagram in Fig. 1.

One of the three cases mentioned had rather peculiar conditions, which necessitated the adoption of another expedient. About midstream there is a narrow rocky island that reaches to about the elevation of extreme high water. Near the edges of this island, as shown in Fig. 2, will be built two small piers,

each of which will support one end of a long span. Between the end shoes will run a temporary strut, and from each pedestal will spring a temporary post to support the temporary top-chord eye-bars that run from hip to hip. The rectangular panel is braced with temporary adjustable diagonals, and the top chord is hinged at the middle and connected to the pedestals by other temporary adjustable rods. These two sets of adjustable rods permit of the raising or lowering of one span at a time. By means of this device more than one half of each span can be cantilevered out to meet the remainder thereof, which will be erected on falsework.