The transition from smelting with a bole or bale to the orehearth is an
interesting phase which marks the first widespread application of
mechanisation to part of Britain's lead industry.It is also one for
which we are still forced to rely on a high degree of speculation.
As Peter says David Kiernan's work made an important contribution to our
knowledge,It has also tended to reinforce the belief that the orehearth
was developed on Mendip (presumably where it was blown by hand operated
bellows) and then transferred to Derbyshire.I've certainly never had
cause to question it until I realised the significance of the early date
given in Ian's email of December 24^th .Nevertheless, the cupola furnace
provides a useful comparison in that it originated around Bristol, went
to North Wales and Tyneside, was in Yorkshire in 1701 and did not
reached Derbyshire until the mid 1730s.
That said, David Kiernan dealt primarily with a period of 70 or so
years, at the end of the bole smelting period, when large structures (7
metres or more across) were involved.There is no indication that
anything like the latter, which suited the levels of production and
system of ore buying adopted in Derbyshire, was used in the mid and
north Pennines where smaller fires were used in bales.One might expect
that earlier (pre C16th) boles in Derbyshire were more like the latter.
Small bales would have the advantage of being more manageable by means
of crowbars to break up congealed lumps of ore/brouse and the use of
fleaks to direct the wind more precisely.One when considers those
implications it seems no great jump to having a more formal hearth,
probably blown by bellows -- the orehearth is born (strange that it took
500 years or more).The shift to waterwheel-powered bellows inside a
building demands a greater input of capital, restricting smelting to
mineral lords and individuals smelters (again largely confined to
Derbyshire).
The meaning of Ian's second reference (suchemynes lede lott [vj c]
groofes balehouses & colys with thappertances) and Peter's roughly
contemporaneous one to 'lead sand' provides more fuel for speculation.
It seems agreed that 'colys' is not likely to be mineral coal, but
whether it is charcoal or dried wood is open to question.
What was a balehouse?None of the people who have studied bale sites have
suggested indications of any significant buildings. It is tempting to
see it as some sort of proto-smelt mill, perhaps containing a form of
bellows blown slag hearth.I suspect that it was more likely some
semi-permanent structure in which the balers could shelter and keep
their tools etc during the smelting regime. They were working on hill
tops after all!
Lead sand -- I agree with Peter that 'fines' is a reasonable
interpretation, and I agree that these "would [probably] have to be
processed by some form of bellows blown (water-powered? = highly
unlikely) smelting technique prior to the introduction of the
ore-hearth."Once again, the smaller, possibly bellows-blown bale might
have had an advantage over the late Derbyshire conflagration type of
bole.Some Derbyshire writers (I think parroting Dickinson's lead) claim
that fines could not be smelted in an orehearth, hence the widespread
adoption of the cupola in that county in the mid C18th.I think that
choice probably had more to do with fuel supplies because mid and north
Pennine smelters used the orehearth until the early C20th.
Mike
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