— 55 — 
plates at thoir lower end»«?, or driven into holes drilled therein. In tho latter case the 
ends of tlie bolts aro split, wedges inserted in tliG slits, tliG bolts driven down lull’d 
so as to sproad the ends; then molten sulphur poured into the holes. 
Expansion is provided for at tlio other peolostal in short spans by a tonguo on 
tlie under side of the slioo pkto fitting into a groove in the upper sulo of the bed 
plate or by such an arrangement as that shown oil PI. II, Fig. 15. In other spans tlie 
shoe plate rests upon a nest of turnod rollers, held in a light framo and rosting on a 
planed roller plate, wliicli has angle iron rivet ted around its edges so a*s to form a 
shallow box : this box is arranged so as not to hold wn-tcr. Tho bottom of tlio shoo 
plat-o is so planed down as to leave along its centre line parallel to tho length of 
tlie bridge a projecting rib about two inches "wide and from an eighth to a quarter of 
an inch deep, which fits loosely into notches turned on tlie rollers. A similar pro- 
jecting rib on the upper face of the roller plate also fifca tightly into tlio notolies on the 
rollors, effectually preventing lateral motion of any magnitude. Tlie reason wliy tlio 
projecting portion of the shoe plate does not fit tightly into the notches in the rollers 
is because, if ifc did so and if the roller plates were not laid more accurately than can 
generally be done in practice, tho end lower lateral strut might prove to be too long 
to enter tlie space assigned to it, or not long enough to fill it completely. Vertical 
motion is prevented by turning over tlie top of tlie outer angle of tlio roller plate so as 
to almost touch the top outer edge of the slioo plate* These pedestal details are all 
illustrated on PI. II Fig. 12, and on PI. IX, Fig. 18. Shoes are sometimes made hinged 
so as to make certain of there always being an even bearing upon tlio rollers, but most 
of tlie best bridge designers do not recognize the necessity for tliis refinement of con- 
struction : its uso would cause an increase iu tlie section required for the batter 
brace. 
Iu double intersection bridges tlie long diagonals are halved and connected by 
pins， passing through tlie middle of tho posts, the channels of which are reinforced 
by plates at tlie pin holes to compensate for tlie metal cut away. Tlieso 1101 es sliould 
be slotted in tlio direction of tho main diagonals, in order that tho extension of tlio 
latter may cause no deflection of tlie post at the midillo, but still permit of figuring 
山 0 post as of half length with both ends 11111 ged. Tlio extension of the counters is 
not so important therefore the pin holes need not be slotted in tlio direction of their 
length. Centre posts, wliicli are crossed by counters only, nearly always have a 
superabundance of strength, so their centre pin holes require no slotting. 
Filling plates are usod for top chords wliore there aro abutting channels with 
Webs of unequal thickness, in floor beams and track stringers to fill tlie spaces bet- 
weeu stiffeners and webs, at pedestals to fill between tlio outer chord bar heads anti 
the webs of- tlie batter brace channels, and at first panel points of through bridges 
below the chord heads so as to make the floor beams at these places on the same 
level as that of the others. 
Lateral struts are connected to chord pins botli in tlie upper anti lower systems 
】)y jaws as shown on PI. YTTT Figs. 1, 2 and 4. Wliere bent eyes are employed for the 
lateral rods there are two nuts of different diameters used for attaching the strut to 
tlio chord pin. The larger serves to hold the jaw against the cliord, tlie smaller 
