Japanese railroad truss bridge, ho would condemn it before getting within a hundred- 
yards of the structure, for all such bridges have pony trusses without any side brae 
ing. This is objectionable for two very important reasons : first there is nothing to 
resist the wind pressure upon the top chord, and to prevent its overturning the truss; 
and second, when the top chord is not held laterally at the panel points or other 
places, its true length as a column must be about equal to the total length of span, 
when considered in respeefc to lateral deflection under load. Ifc is quito evident that 
no pony trusses in this country have their top chorda proportioned for tho number 
of diameters found by dividing the length of span by the width of top chord plate. 
As tho before montioned inspector would approach tlio bridge I10 would bo 
struck, in fact liorrified, by tho nbsoluto lack of laterfil bracing j for one oannofc im- 
ftgme that tho n vetting of the floor beams to the lower chords by four rivets at each 
end can give any lateral strength to tlio bridgo wlion subjected to wind pressure. 
Ther “ 8 i ust as much reason in this arrangement as there would ba in omitting the diago- 
nals from the trusses and rivet ting the vevticcil posts to the outside of the top and bottom 
chords. Such an arrangement might sustain a small balancod load, but an unevenly 
distributed load would certainly destroy the structure. The Japanese truss bridges 
file therefore wholly unfit tod to resist the strossos produced by a wliirlwind. 
ThG next thing that would catch tho inspector’s eye would be the inclined struts 
of tlie Warren girder, formed by trussing, in the most inefficient manner possible, 
two very thin, wide bars. Such struts were experimented upon years ago in Ame- 
lica and were unhesitatingly condemnod. It needs no experiment, though, to show 
their inefficiency ; for theory teaches that tlio strength of a strut increases with tho 
radius of gyration of its section in respeefc to the neutral axis of that section ； audit 
is evident to all that a flat bar lias a very small radius of gyration. 
The next parts that tlie inspector would notice would be the chords. In tho 
upper there is a waste of material at all points except the centre ； and the box form 
of the lower would condemn it immediately in hia eyes. Concerning this point let 
me give you the opinion of A. P. Boiler, Esq. C. E. , a well known American engin- 
es of acknowledged ability, as expressed in liis treatise on “Iron Highway Bridges." 
“In continuous box-shaped chords, the pin holes must be reinforced with thick- 
ening plates, not only to increase pin-bearing, but also to distribute the pressuro de- 
livered to tlie chord at each panel point over as much surface as possible. Further 
it is advisable that the increased nectional area required at each panel point, in ap- 
proaching the centre, be placed in the sides of the box. as it is through the sides that 
the pin passes. It is not one of tho least excellencies of the pin-connection system 
that the chords, posts and tension-members may be made to unite at the centre of 
their several sections, and by proportioning the box cliorcl as above this may be ac- 
complished very fully This principle is about as far lost sight of in rivet. 
ted work as ifc is possible to be. In such work tlio chords have no stiffening along 
the inner edges of the vertical plates or sides to which tho web system is rivetted, 
and the increase of area is made by rivet ting on plates to the upper side of the top 
chord, or lower side of the bottom. The centre of section is not at the middle of the 
sides, as usually assumed, but approaches the top or bottom plates, and in largo 
