TIMBER BRIDGE CONSTRUCTION IN N.S.W. XV. 
Thus it will be seen that there is a saving of £50 per annum 
in favour of the timber bridge, which has at 4 per cent. interest, 
a capital value of £1,250. See Plate 8. 
The author has also designed timber trusses for spans of 130 
feet and 153 feet. The latter truss altogether differs from the 
Wagga Wagga bridge, four flitches instead of two being placed 
in the top and bottom chords, and as for purposes of renewal 
a larger sectional area is provided than is actually required for 
direct tension, the floor beams can in this case be seated directly 
on the upper edge of the bottom chord. 
The flitches of chords being spaced only three inches apart 
whilst allowing of a free current of air, and room for painting, 
permits of the adoption of channel iron gib-plates for suspension 
rods in lieu of the heavy forgings used at Wagga Wagga, whilst 
the castings are, from the same cause, much lightened. 
Again, in the lower lateral system diagonal timbers and trans- 
verse tie rods have been arranged for, which is somewhat more 
economical than the diagonal tie rods used at Wagga Wagga. 
In conclusion the author desires to record his acknowledgments 
to Mr. Hickson, .1.c.£, for his courtesy in lending models, plans, 
and photographs to illustrate the several works mentioned in the 
foregoing paper. 
DIscussIoN. 
Mr. Deane said that in a design for a timber bridge, in the 
first place there was the proportioning of the amount of material 
in the trusses, and beams to the strain to which they were sub- 
jected. That of course should be made as near to theory as 
possible, although it was hardly possible to strain right up to 
theory. The different parts should be capable of separate erec- 
tion, and ought to be put together in a proper manner, for 
instance, the trusses should be stayed, and should be capable of 
erection separately ; they should be complete in themselves, and 
braced together before any attempt is made to put on the plat- 
