( for the moftpart triangularly built, and iac^d we!i \vi"h 
free-ftone) oppofing, and breaking tlieftream feveraliy, 
I mean, not altogether, or at the fame time, by reafoii 
of their various inequalities in ftanding out: in cafe the 
flood fliould fwelHo high ("as it frequently does) as to co- 
ver both the Pedeftals, then the fmall Arches dividing 
the feet of the great ones N. 3. help to convey the 
water through, which otherwife might endanger the 
great Afches. This Sir, is all I conceive at prefent, I 
mean as to the fuperficial defign, whether there is any 
particular Architedlure within the Pedeftals, or at the 
feet of the Arches within them^ or in the general fabric 
of the Bridge irfelf, I cannot tell ; no body being able 
to inform me : or whether the J{omans had fome peculiar 
Cements not known to us, 
j4 ^mar\about the foregoing Letter by T)t,l::A,l^^ 
Note that what feems the foot of the Arch, h 
an Hori'^cntal Arch gradually contraded, every ftooe be- 
ing ot vaft length and wedge like, laid level with the 
water. Thislfpeakby memory, and in this particular 
I did moft defire to be fatisfied^ becaufe it might be oi 
great ufc and advantage in building our Bridges in Yorh^ 
Jhire, whofe ftreams are moftly Torrents, as the ^ojne 
is the greateft in Chrijiendome, and ours modly as that 
have rocky bottoms, which will not admit of Piles dri- 
ving in. - 
An 
