A defcription of a Bridg that may be built 70 foot long 
without any vi]l?ir under it ^ taken out of the ]ouv- 
nal of //jePhilofophical Sociecy (^/Oxford. 
A Timber Bridge may be built 70 foot long or fome- 
what more without any P///^r under it, which may 
be ufeful in fome places where Pillars cannot conveni- 
ently be built : It may conlift of two fuch Arches ot Tim- 
ber, as that which is reprefented in the Figure, where- 
in AC and BO are Beams 2 8 loot long, and AB is 3 2 foot 
long. Under the Angles arefet2 large Braces EL and 
SR. A t each end is a wall, on which are laid two Beams 
BH and AD, each 20 foot long 5 under thefe are 2 Braces 
DE and RH. There may alfo be Braces at the ends ot 
the Arches, that may be obliquely crofs the Bridge. It 
may be laid with Planks and railed. Behind the walls 
are Caufeys FD and HN. The Length of t\\Q Bridge 
CMO is 70 foot 5 the Height KM is 19 foot. 
Obfervations 
