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| grinding and if the Instrument is attempted to be withdrawn the holes imme- | ||||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