4(5
Dunkeld Bridge, Perthshire.(Aberdeen granite.)
c = 48.5 feet, n = 8.1? feet, g = = 164 lbs. f
— 9581 feet, w' = n — 1 ) = n — x ) — 3.17 X
196.54= a prismatick column of the same materialof one square foot base 623 feet high, and 623 x164 = 102172 lbs. avoirdupois on a superficial foot,which is the limit of weight the bridge is capable ofsustaining at the vertex.
The foregoing bridges are not built with ribs orarcs doubleaux.
Tete, Picardy.(Fir)
c = 319 feet, w = 3.834 feet, g = — = 3 7-5 lbs.
f' = 7680 feet, w' = n (£- -i) = n ~ 2 ) —
X 23.07 = a prismatick column of the same material,one square foot base 88.45 feet high, and 88.45 x
, QQ 1 >7 *
37.5 = 3317 lbs., and —— = 1106 lbs. avoirdupois
(7 -*) = w (
40 times lj inches, tu — n
14302
112.5
- 2.6) = 40
X 124.5 = 4980 lbs. on a linear foot 1| inches wide and 4980x 8 = 39846 lbs as before on a foot superficial.
* A wooden bridge being generally composed of frames at adistance from each other, equal to twice the width of the frame,.