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Document 35, p 12

Barr above mentioned (which was tried in several places across the River)
determined his Judgement that what he had felt and experienced was sufficit
It may here naturally be enquired, why Mr Smeaton did not Bore
the Bed of the River, instead of driving the Barr, in the manner described:
And he Answers, because former Experience had taught him to have very little
faith in boring in Gravel for the purpose of founding Bridges for the Colliery
borers, though exceedingly expert in Boring to the purpose for which they are to
apply them, yet are no competent Judges of the compactness of the Stratum for the
purpose of Building a Bridge, and in the Trials formerly made by Mr Smeaton
himself from the continual falling in of the smaller parts of the Gravel itself while
the shank of the Instrument is turning round, therby occasioning a continual
grinding and if the Instrument is attempted to be withdrawn the holes imme-
-diately filling made it never appear to him in the light of a satisfactory oper-
-ation convincing to his Mind of any certain conclusion he has therefore for many
Years past contented himself with Trials by the Barr which being driven by an
Hammer he judges of the Compactness of the Gravel by the number and strength
of the Blows that it takes to get it down, and on the Faith of Trials of this kind
where the Barr went down with a Competent resistance, and a near Equality
that he built the Bridge of Perth upon Piles encased with sheeting.
From a mature Consideration of the above Particulars and Circumstances
Mr Smeaton found himself lead to the following Conclusions Vizt:
That to build a Solid Wall across the River as a Foundation for the whole
Bridge in the manner proposed by Mr Wooler would not only be attended with an
enormous expence but in the place he proposed it likely to be in itself
impracticable for it did not nor does not occur to Mr Smeaton how this is to be
done without draining off the water from the bottom of the very large Excava-
-tion that would be necessary to be laid open at once which must not only go
down into the Quicksand but in reality considerably into it to lay the proposed
Foundation of the Wall that in case the Quicksand should break up and run
as it was most likely to do that then the damage of this Liquid matter would
12 be

Note: Mr Smeaton's Memorial, p 12

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Transcribed by CTW