A 
JOURNAL 
OF 
NATURAL PHILOSOPHY, CHEMISTRY 
AND 
THE ARTS. 
MAY, 1813. 
ARTICLE I. 
Method of constructing an Iron Bridge , with one arch of exten- 
sive span. Proposed to le carried over the Menai between 
Anglesea and Caernarvonshire. By Thomas Telford, Esq. 
Civil Engineer*. 
T HE other design, plate I. is for the narrower streight Bridge over 
called Ynys-y-Moch. Here the situation is particularly tiie MeuaI ’ 
favourable for constructing a Bridge of one arch, and making 
that 500 feet span, leaves the navigation as free as at present. 
In this I have made the height 100 feet in the clear at high- 
water spring-tides, and I propose this bridge to be 40 feet in 
breadth : — estimating from drawings, as already described, I 
find the expense to be 127,33 s/. or 31,307/. less than the 
former, f From leaving the whole channel unimpeded, it is 
certainly the most perfect scheme of passing the Menai, and it 
would, in my opinion, be attended with the least inconvenience 
and risk in the execution, 
* From liis Report to the Lords of the Treasury, April 22, 1811. 
t Two designs are given in the Report ; one for the bridge here 
described, of a single arch, at Ynys-y-Moch, about 800 yards to the left, 
or south-westward, of Bagnor Ferry, and another of five arches at 
about twice that distance upon the Jfwilley rocks, estimated at 158,698?. 
Vol. XXXV.— No. m, & la 
