— 225 — 
If there be two tiers in a bent or one tier resting upon piles which project more 
n live feet above the surface of the ground, inclined posts having a batter of two 
0 to the foot should be placed outside of the vertical posts under th« trusses. 
Each tier should be braced with diagonal timbers, as before. The greater the 
n g er of high wind, the more effectively should each bent bo braced« Alternate 
secutive bents should also be braced diagonally on their outer laces, and all 
°usecutive bents should be connected by longitudinal horizontal planks well spiked 
6 C . a P s . These planks will be useful, in fact often necessary, for tlic workmen 
0 - f acing from bent to bent. If there be more than two tiers per bent, tlie batter 
• e inclined posts should be three inches to tlie foot, A good height for each tier 
8 Slx teen feet. 
j, Where tlie water is deep and rapid, piles will be required to rest the bents upon. 
a 6le 8 houl(l be from two to five piles per bent, according to tlie width of the latter ; 
e eing placed below each vertical and inclined post. These piles should be 
that GC ^ direction of tlie stream by flat timbers bolted thereto. Any bracing 
匕 may be given them transversely to the stream should be at such a distance above 
0 hjec_: a t er l eve l as to cause no obstruction to boats, trees, ice, or other floating 
^ Ö the bottom be bare rock, incapable of holding piles, the mud- sills must again 
如 .= 01 ted to. They should be weighted so that they may be sunk into place, tlien 
8 ills 也 61 ! to the rock. This can be done without tlie aid of a diver. Of course tlie 
= u st be firmly attached to the lower tier before being put down. 
ai,e ^ 1G t 0 P 8 of 认 U piles should be cut off to an exact level, so that, when the bents 
e 二 ected, tlie upper surfaces of tlie upper caps will lie in the same horizontal plane. 
^ ese ca P s should be placed timber-beams stretching from one bent to the 
the ひぬ i mai ediately under the trusses. It is generally customary to place 
が Gn ^ s Uü der tlie panel points ; but the author prefers to put them two ieet to one 
^lse S ° the floor beams may be swung into place without taking down tlie 
0 £ 仏浓。 1 ]、’ This method may, and probably will, require an extra bent at one end 
8 P au ； so, if fclie bents be expensive, it is better to put one under each panel 
l and remove the upper tiers before swinging the floor-beams. 
和 he T 8 P ans ' v here tlie track stringers rest upon the floor beams, or for any spans 
of ^ e bents of falsework are directly under the panel points, the level of the top 
So : ° u gitudinal beams should be at least twelve inches below tlie feet of the posts, 
an gle P. erm it of the use of camber blocks, like those shown on Plate XI. The 
a ü ^j e the contiguous faces make with the horizontal (less, of course, than the 
t]i fi 0 ° fiction of tlie wood) enables tlie under block to be easily knocked out wlien 
swung . 
t 0 0llG U ' で 01 ’ the case of stringers abutting against floor beams, and falsework bents 
心 t. び 山 6 panel points blocks must be placed between tlie cambre blocks and 
lower f i G1 ^ eaiüs » 80 that tlie track stringers may pass oyer the upper caps of tlie 
se ^ with a couple of inches clearance. 
the siz 说 Ambers for the caps and posts of the falsework are generally square, and 
Zesfortlle latter are to be found from Table XXIV., after tliq stresses in 
