— 172 — 
wlncli is near enough for all practical purposes to the 21.8" required by tlieory. 
The next details on tlie “ ljist of Members are the reiiiforciug plates at tlie 
feet of the posts. Table XV. gives for a boariug stress of 18.6 tons and a 8 piu a 
bearing width of -} rr f subfcractiug from which 0.325, the web thickaess of a 12" — 
22i’[, loaves 0.55 aa the thickness to bo furnished by tlio outsido and iusicle rein- 
forcing plates, from which it is evident that tlie least allowable tlückness of will 
be sufficient for each. 
Let us assume that half of the 18.0 tons is borne by the inner reinforcing plate, 
ami the remainder by tlie outer plate and tlie web. Tlie moment of stress on the 
rivets will then bo 9.3 x .y ( 普 +0.3 部 ）= 3.255 inch tons, which divided by 0.3111 the 
working bending moment for a rivet gives 11 as the namber of rivets required 
to resist bending. 
Tlie total pressure on the rivets cannot exceed 
18 - 6 ( 2 X r+kääs) =ab0utl3t0as> 
which divided by 1.46, the approximate working bearing pressure for a i" rivet on a 
plate 0.32 5" thick, gives 10 as the number of rivets required for bearing. It will be 
bettor to uso a greater nuiuboL , of rivets than the calculations call for, because tlie 
roi a forcing plates should extend a few inches higher tliau the lower edges of the 
stay plates so as to stiffen the otherwise unsupported projecting ends of the post 
channels. A drawing to scale would show the height required to bo about 2’ mak- 
ing the total length of tlio inside plate 5' and that ol the outer say 2.4’. These 
tli mentions are applicable to fclie other post reinforcing plates, tlie widths for which 
should be equal to the depths of the cliannels to which they are attached, provided 
that; sucli depths be not less than 8". These dimensions are entered on the “ Bill 
of Iron.” 
Next come the plates for connecting tlie intermediate struts to the posts. 
It is not worth while to make any calculations for this counecfcioii, because the 
stress on the strut is eo small. 
We will use two bent plates each 象 " 4" x 2.5 , A simple calculation shows 
that the cliamefcer of tlio pin for attaching tlio vibration rocl should be 1J 7 , 'vliicli 
would leave 1 l f, of iron outside of tlio pin hole, which is sufficient. 
Next come tho plates for counecting tlio lower portal struts to the brackets, the 
dimensions of which we will assume to be x 0 r, x 15". 
Next come those for connecting upper portal struts to name plates, tlie size for 
which we will assume to bo ゐ " x 9" x 2\ 
Next come tlie connecting plates for track stringers over floor beams, the dimen- 
sions for wliicli may be taken as ^ ,r x S r, x 
Next come the cover plates. The length of tliose at the hip may be taken ⑽ 
2', feu. they carry no stress that can be calculated. 
Tlie stress carried by any intormeduite cover plate is f x 20 X3.543 = 26.57 
tons, which multiplied by f gives 9.96 inch tons as tlie moment on the rivet's. 
Using l n rivets we have 
