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Document 29, Report from Robert Mylne to Northumberland Magistrates, 24 April 1783, p 1

58
		Hexham April 24th 1783
	To the Magistrates and Justices of the Peace in and for the County of
	Northumberland in general Meeting assembled
Gentlemen/
Being requested by you, to view & examine the present State of the Bridge across
the River Tyne lately Built by, & at the Expence of Henry Errington Esq agreable to the Plan
& Advice of Mr Smeaton, & to inspect the scite* & Nature of the Bed of the River, whereon the
same was constructed; I beg leave to Report that it fully appears, this Bridge was under-
mined by the great Flood, which happened on the 11th Day of March 1782. And that the Soil
& Substance, of the Bed of the River, of whatever matter & quality the same consisted, was
dug or scooped up, from below the greatest part of the Piers, & that towards the West
or upper side, of the Bridge; And the advanced or Guard – works inclosing a Space
round the Piers, for the better Security & Maintenance of the Soil, immediately under
the Piers, whereon the whole weight of the Structure had been charged, were also under –
mined, by the Gravel & sand, into which they had been driven, being worn away by
the Velocity of the Stream; thus circumstanced during the heighth,*, & greatest Rage
of a Flood, it will appear no wonder that the Piers, having a forth, half & even to ¾th
of their Base, taken out from below them, the Arches split in two, longways; by some
of the Piers breaking across, into two parts, precipitated into Ruin themselves, & the Parts
constructed upon them.
All the Piers fell toward the Stream, but took different Inclinations towards the Excavation
of the Bottom, sometimes made more on one shoulder than on the other of each Pier.
The Surface of the Water line is now 22 Inches below, than the time during which
the Bridge was constructed, I have bored the River at the Bridge, to the Depth of 23 Feet
below the latter water level, in a place where I might not be led astray, by any Alteration
formed by the said Flood, in the heighth of its Impetuosity; And skimm'd over again in
its milder Velocity; And I have found under the Testimony & Perseverance of Mr. Wake
that the Soil & Texture of the bed of the River, at this place, is uniformly a Composition
or congeries* of Roundish & flat Stones, gravel & Sand, of equal Quality & Consistence in
the whole of that Depth.
The Piers which were founded by means of a Batter deaux*, have stood tolerably
well, & those which were laid by Caissoons*, having no Piles directly under the Piers, were the
easiest prey to the vast powers of this Flood.
The Depth to which all the works in general whether immediate, or preservative
were far too shallow, & too little into the Bed of the River, which, (tho hard to the touch of
boring, & compact to the Eye, & feeling of Instruments) is wonderfully loose, & connected in
its parts, in so much, that the Bed of the River Tyne seems to shift, & alter its form
extent & variation with every Flood, more or less, & tearing up at one time to a great
Depth that fair moulded & well laid hollow, which the Stream had laid for itself,
on some former Occasion.
In such a Situation, under these Circumstances, with the additional one of
many Piers being to be fixed obstacles to its Violence, the foundations could not be
laid too low; to what Depth they ought to have been laid, & the means to be devised for
that purpose, lay & remain with the Parties engaged in that Performance.
Mr. Smeaton than whom, there is no Person or Artist better instructed, more
knowing, & of a more penetrating & correct Judgemt, must have been decieved in the Collection of
facts

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Transcribed by KS and PF