to resist the pull of the lateral rods : of course tho pin has to be shouldered down, 
and it is evident tliafc it should be inserted from tlie outside of the bridge. Jaw plates 
are either single or double ； the former wliere a special vertical pin is used for tlie 
lateral rod attachment, the latter wliere the rods are connected to the chord pins by 
benfc eyes. Tlieso bent eyes aro not used on rods exceeding one and three quarter 
inches in diameter. The function of tlie inner jaw plate is to reduce the pressure of 
the bent eyes upon the mit on the end of tho chord pin, and to avoid tlie oblique 
action of the same. This oblique action is not so objectionablo in the case of light 
rods pulling against well proportioned bolts and nuts, as in tho case of some vibra- 
tion rod attachments. 
Portal braces are connected to tlio batter braces b t y large sliort bolts through 
tlio medium of single jaw plates as shown on PI. VIII Figs. 3 and. G. When tliere are 
vibration rods at the portal the portal stmt channels are placed closely together with 
their webs parallel to the piano of tlio batter braces, in which case one bolt through 
each jaw is sufficient ; but, when there are no vibration rods, the portal strut chan- 
nels are spread far apart with tlieir jianges parallel to tlie piano of the batter braces, 
in wlncli case two bolts through eacli jaw will be required. Portal vibration rods aro 
attached to the struts by pins as shown on PI. VIII, Fig. 8. 
Ena upper lateral rods, if small, may be attached to tlio liip pins by bent eyes, 
provided that the nuts for said pins be well proportioned ; but, when they exceed one 
and three quarter inches in diameter, they are coupled by split eyes to special verti- 
cal pins passing through the flattened ends of the hip pins as shown on PL VIII Fig. 5. 
Intermediate vibration rods are attached to upper portal and intermediate struts 
by bolts or pins as on PI. VIII Figs. 2 or 4. 
Intermediate struts for single track bridges are connected to tlie posts by two bent 
plates at each end as shown on PI. VIII Figs 2 and 4 ; those for double track bridges 
l>y jaws. 
Knee braces or brackets are used to connect upper lateral, portal or intermediate 
struts to posts or batter braces. Where no vertical sway bracing is used these knee 
braces are very important portions of the structure, and have to be proportioned to 
resist calculated stress, but where isway bracing is employed tlieir uso is principally 
ornamental. They can be in ado of either angle, channel or tco iron ; preferably tho 
former : they are not to be bolted but rivetted to the parts wliicli they connect. Side 
braces are to be connected to tlie top chords and floor beams as shown on PL IX 
Figs. Iß and 17. 
There are two different floor systems, to be described presently : in tlie first of 
tliese the lower lateral rods pass through the wooden sliims ; and tlio lower lateral 
struts between tlie ends of tlie track stringers ; bufc in tlie second both rods and 
struts pass through holes in the webs of tlie strmgers. The first system is shown on 
PI. Ill tlio second on PI. IV. 
Floor beam>s are liung from bottom chord pins by beam liangers, formed of 
square iron with enlarged ends, which is bent into tlie shape of tlie letter U. The 
ends of the hangers pass through holes in a plate, called a beam hanger plate, which 
acts as a sort of stirrup for tlie floor beam、 Nuts on the ends of the hangers are 
