—— 166 — 
Next lefe us calculate the size of the pin at the top of the end vertical post. 
The chord bearing is given by the equation 
B = ^ + 0.75 = 2.1" Say 2 会〃 
and the post beariug by the equation 
B = - 1.14 " sa" U 〃 
These quantities make the lever anus 
I = i ( 1* + H M " say 1 " to allow for play, 
and Z / = ^ ( + Ü) +H= " say 2 ド to allow for play. 
We must again suppose tlie outer bars with tlieir stresses not to exist, therefore 
the vertical and horizontal components of - = 11.3 tons, determined graphically 
to be respectively 8.6 and 7.3 tons, are the stresses to be considered as producing 
the bending. 
The vertical and horizontal component moments are therefore respectively 
V = 8.6 x 1 = B.C inch tons 
and H = 7.8 x = ： 19.2 inch tons, 
making tlie resultant moment 
M = V ( 19.2)2 + (8.6) 3 = 21 inch tons, 
corresponding to a diameter of 3 長 ’’. 
As there are but two diagonals in the. next panel, the stress on one will be 18.5 
tons; and as the lever arms are but slightly greater in this case than in the last, 
we can obtain the resultant moment approximately by multiplying the preceding 
value by 器 or 1.2, making the required value 25.2 or say 29 inch tons to allow for 
the slight increase in the lever arms. This corresponds to a 3i^ # pin, which dimen- 
8ion will not only be adopted for this panel point, but for convenience also at the 
end of the outer vertical post. 
The same diameter may be adopted for the middle pin, or its proper size may 
be determined in a similar manner. 
The total stress on the counter is 9.746 tons plii3 the initial tension of 8.83i 
tons, as given in Table YI., or 13.080 tons. 
Tlie half of this stress, 6.5 tons, passes to each side of the post and to each side 
of the chord, or would do so if a double eye were used on one counter. The vertical 
and horizontal components of this stress determined approximately by scale are 5 
tons and 4.2 tons. The corresponding lever arms may be roughly taken as 5 inches 
and six inches respectively, making the component moments 
7 = 5 x 5 = 25 inch tons 
and H = 6 x 4.2 = 25.2 inch toii3 
