一 - 99 — 
where nt ( greater than | ) is the number at that end of the panel considered lying 
next to the lietircr end of tlie spjin \ ioi* tlic bottom chord in these c<iscs tiiUcs its 
greatest stress when the leading engine excess is nt that end of the panel considered 
fartlxest from the centre of the spau. 
•Tlie last formula fails for tlie case of n, middle panel, when the liuiüber of 
paiiela is odd. In this case the stress is given by tlie lormula 
lu clouble-iu tersection trusses tlie stress in any other panel of tlie bottom clioul 
than the first or second is given by the equation 
T= 2 ( V — 1 ) O 二 a 
kliere n t (not less Ümn 尝 + 1) is as before tlie mimber at the entl of tlie panel 
farthest from the zero end of tlie span. This limitation excludes the culculaliug l>v 
this formula of the stress in tlie miiltlle panel of every truss having an odd 
mimber of panels ； but such a calculation is unnecessary, for tlie greatest eugine ex- 
c es 3 stress in the midillo panel is equal to that in the next consecutive panel. From 
Uüs formula it is apparent that all tlie panels of tlie bottom cliord, excepting the 
first and second from tlie ends, take their greatest stresses when the engine excesses 
ai， e separated by a panel point. It was seen that such is rarely the case ^vitli tlie 
top chortl panels. 
Tlie engine excess stress in fl-ny main diagonal oi* counter of a single intciseo 
tio n truss, iu which the panel length is not less tlian eighteen feet, is given by tlie 
equation 
T = (2 rJ- 1 ) ^ sec 6 ； 
a ud, if the panel length bo less than eighteen feet, it is given by the equation 
r = 2 1 ) ― sec 0 
For double intersection trusses tlie corresponcling formula is 
j? 
T = 2 1 ) ^ec a, (or sec ß ) 
F or single intersection through or pony truss bridges where the panel length is not 
less than eighteen feet, tlie engine excess stress on any post is given by the 
fonnula 
O— (2 n'- -6) - ; 
auc l» where the panels are less than eighteen feet, it is given by tho formula 
C = 2 いし 2) 会 
