Dataset – Peter King

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The production and consumption of bar iron in early modern England and Wales

Economic History Review LVIII, 1 (2005), 1-33
P. W. KingHonorary Research Fellow, Birmingham
These web pages contain the otherwise unpublished data used to create the charts and tables in the above article. For the most part they reproduce data set out in the appendices to the author’s unpublished thesis, ‘The Iron Trade in England and Wales 1500-1815: the Charcoal Iron Industry and its Transition to Coke’ (PhD thesis, Wolverhampton University 2004). The data range was chosen, as covering that in what charcoal-fuelled blast furnaces were in use.
Copies of all computational files (but without formulae etc.), the thesis text, and other related documents are held by Archaeological Data Service.

Anyone wishing to re-examine the computations in detail will need to obtain a copy of the CD-ROM appended to King, ‘Iron Trade’, which includes all such files (and more). This is available from the author via Blackwell Publishing (Publishers of Economic History Review) [].

A. Raw data:
1. List of bloomery forges – from King, ‘Iron Trade’, appendix 9
This list consists of known sites of bloomery forges, also known as bloomsmithies (or just smithies). These were water-powered ironworks, reducing iron ore to the metal in the solid state. They were probably introduced to England and Wales in the 14th century, but began to be replaced by blast furnaces and finery forges from c.1490. However the process remained in use in northwest England until the 18th century. The data have been collected from a wide range of sources. Nevertheless, the list is almost certainly incomplete due to a lack of surviving source material, and because much of the period was before that studied for the thesis, and concerned a process that was relatively insignificant subsequently. This list may need substantial revision in the future, but this is unlikely significantly to affect the conclusions of the author’s article.

2. List of Wealden forges – from King, ‘Iron Trade’, appendix 10
About 1490, a new process was introduced. First pig iron was made in a blast furnace, then (so far as not used to make finished goods of cast iron) this was remelted and fined in a finery forge to make bar iron. The data here are largely taken From H. Cleere and D. Crossley, the Iron Industry of the Weald (2 edn, Cardiff 1995), as supplemented (mainly for the 18th century) by P.W. King, ‘Bar iron production in the Weald in the early 18th century’ Wealden Iron 2 Ser. 22 (2002), 26-35. Where dates are given as ‘0’, the dates of operation are unknown.

3. List of Wealden furnaces – from King, ‘Iron Trade’, appendix 11
This is the counterpart for blast furnaces of the list of Wealden Forges, and relies on substantially the same sources.

4. List of finery forges elsewhere – from King, ‘Iron Trade’, appendix 12
This represents the first publication of any reasonably comprehensive list of finery forges for periods before the 18th century, when there are a series of contemporary lists. For those lists see E.W. Hulme, ‘The statistical history of the iron trade’ Transactions of the Newcomen Society 9 (1928-9), 12-33 and P.W. King, ‘Early Statistics for the iron industry: a vindication’ Historical Metallurgy 30(1) (1996), 23-46.

The other sources for this compilation are far too many and varied to be fully described here. The most important are the archives of landed estates that were the landlords of ironworks, not only leases, but also rentals and surveys, and descriptions in estate title deeds. This is supplemented by references to one ironworks (as a supplier of raw materials or a customer) in the accounts of another, and from evidence of other aspects of trade. Land tax assessments (which survive for most counties between 1780 and 1830) have often been useful for determining closure dates. This remains to some extent work in progress; in some cases, further sources have come to light, which have altered the author’s views slightly since the submission of his thesis in April 2003. Such changes (which are not reflected in these data), have usually concerned the ownership of a forge, rather than its dates of operation.

This body of work is intended to form the basis of a series of books on the charcoal iron industry of which the latest drafts (at the time that the author’s thesis was completed) form part of a CD-ROM appended to his thesis. Its primary objective was to work out who owned each ironworks and at what dates, and how the various ironworks related to each other in terms of trading relationships and competition. However, any available data were collected that indicated the output of an ironworks. The most important source of output data are the lists and surviving accounts, but output may also be indicated by the quantity of wood (for charcoal) bought or the quantity of pig iron supplied to a forge; in both cases, the existence of other sources cannot be ruled out and the resultant figure accordingly will be a minimum output. The software used for the calculations allowed for one period of temporary closure; for few forges, there were two such periods, the second being dealt with by treating it as a separate forge. In other cases, output data was apportioned, where aggregated in a list.

Most entries occupy two lines. The first consists of the name, location and dates of the forge (with its regional classification). The second contains a series of dates and numbers: 1716/150 means that the forge made (or is estimated to have made) 150 tons of bar iron in c.1716. This may be followed by a comment, or there may be a comment on the next line.

5. List of blast furnaces elsewhere – from King, ‘Iron Trade’, appendix 15
This derives from the same body of work that has been described for forges in the preceding section. However, there is must less 18th century output data. Furthermore, the size of blast furnaces was growing in the preceding period; their output data has thus been found to be of limited use in estimating the size of the industry. The data is primarily used in the article to count the numbers of charcoal and coke blast furnaces respectively. Its use is indicated in the final column, but otherwise the conventions are similar to those for finery forges. Where an ironworks contained several blast furnaces, they are listed as separate ones but at the same location. Temporary closure dates have been adjusted so that the number in use at the date of a list conforms to it, but this should not be taken as evidence of which furnace was actually out of blast. The software used for the calculations allowed a charcoal furnace to be converted to coke, but not vice versa. In one case (Cleator), the list indicates that a charcoal furnace was ‘built’ when a coke one ‘closed’; this is of course the same furnace, but now using charcoal.

6. List of melting fineries – from King, ‘Iron Trade’, appendix 14
Melting fineries existing in c.1790 are listed in Birmingham City Archives, B & W, MII/5/12. A limited amount of data from other sources has also been used. These melting fineries seem to be for the process often referred to today as ‘potting and stamping’. Where the ‘closed or converted’ date is not identical with the closed date, it was subsequently used as a puddling furnace; there is thus some data on them, but all data after 1790 is also incomplete. The ‘pig yield’ is the amount of pig iron (in cwt.) required to make a ton of bar iron. The lower (better) figure refers to works (in the Midlands) that were using Wright and Jesson’s process; the higher to ones, which were still using the original (less efficient) one patented by Charles Wood.

7. List of slitting mills – from King, ‘Iron Trade’, appendix 16
The contents of this list have not been used at all in the calculations for the article, but it is included to show that the ironworks have been intentionally excluded from them, because they were not finery forges.

8. List of other ironworks – from King, ‘Iron Trade’, appendix 17
The contents of this list have also not been used at all in the calculations for the article, but the list is again included to show that the ironworks have been intentionally excluded from the calculation. The list includes plating forges (which are water-powered but did not make iron), tinplate works, and spurious claims of the existence of a forge. It also includes forges with a balling furnace, but no finery or melting finery. These seem to have been used to recycle scrap, rather than to make iron. The production of iron from scrap has been excluded from the calculations.

9. Import data collected from Customs Accounts and Port Books – from King, ‘Iron Trade’, appendix 18
Before 1697, no trade statistics were officially compiled. Accordingly, data has to be obtained from records compiled in connection with the collection of Customs duty. These fall into two groups – Customs Accounts (PRO, E 122) and Port Books (PRO, E 190). The former were part of the formal process by which the Customs officers in head-ports accounted to the Exchequer, while the latter were provided by all ports, in theory to enable the accounts to be checked. A large number of each has been examined. The list includes some 18th century data (which has not been used for calculations). For technical reasons in connection with the calculation it has been necessary to insert certain null entries, to avoid the results being distorted, where the import figure for a particular port is included in that for another.

B. Compilations:
10. Production of iron in finery forges
This is figure 1 of the article and the data lying behind. It has been prepared by applying certain multipliers to the number of Wealden forges and interpolating the data on forges elsewhere. The Regional classification system used operates at three levels, region, district, and group. Details of this will be found in King, ‘Iron Trade’, Appendix 7.

11. Iron production in melting fineries
This is figure 2 of the article and the data lying behind it.

12. Output estimates
This reproduces figure 3 of the article and the data lying behind it. Note also a version of the graph with a different scale on the y-axis. The growth rates of the total, calculated over 7 and 21 years, are also given.

King12B Table1 and King12Brevise
This is the data in table 1 of the article, but for every year, not every fifth or tenth year. The same bar iron production section is the same as the previous set, but with furnace data alongside. The calculations in respect of pig iron in the 18th century are intricate, and are not shown. The version of this file originally uploaded contained erroneous data on charcoal iron production after 1788. This was due to a change in methodology, which meant the column in a source file was used for something different. The error was discovered a little while after publication, and a correction was subsequently published: Economic History Review, LIX, 1 (2006), p. 264. This states that the dataset had been corrected: due to a misunderstanding between the author and the editor, that did not happen until 2015.

13. English bar iron imports – King, ‘Iron Trade’, appendix 19
This is the data lying behind figure 6 of the article. It incorporates the result of interpolating import data collected from Customs Accounts and Port Books, together with data for Gothenburg and the Baltic from Scandinavian sources, and data from the Customs Ledgers (PRO, CUST 5 and 16). Data for 1790 to 1808 have been recovered by deducting Scottish data (PRO, CUST 15) from those for Great Britain (PRO CUST 16). Data for 1705 and 1813 (which is missing) has been interpolated.

14. Bar iron re-exports and exports from 1697 – from King, ‘Iron trade’, appendix 20
The sources are PRO, CUST 5, 15, and 16 (as for imports). Exports were insignificant until the 1790s.

15. Exports of wrought iron and of nails in the 17th century – from King, ‘Iron Trade’, appendix 21
This consists of modest amounts of data extracted from mid and late 17th century port books and other sources.

16. Production and consumption estimates – from King, ‘Iron trade’, appendix 23
This is the data lying behind figure 8 of the article; it is the same as in table 2 of the article, but for every year, not every fifth or tenth year.

C. An Afterword
When the Economic History Society website was rebuilt some time ago, the datasets were not carried forward to the new website. Accordingly, the requisite files have again been provided by the author, but this time including the corrected furnace output estimate (section 12 above).
In the light of the need for a fresh upload of the files, the author is taking the opportunity to provide his own assessment of his own past work. Further research in the decade and more since the original publication indicates:

  • A few errors in the underlying data on the dates of finery forges during the core period of the estimate (1550-1815), but few enough not to render the overall estimate significantly inaccurate.
  • Data relating to the 1830s, which is wholly derived from the output of coke furnaces, are of questionable reliability.
  • Data on the production of charcoal forge iron in the early 19th century are likely to the significantly underestimated: its continuing production, probably involving a different kind of hearth, has since been described (mainly for Shropshire) in R. Hayman, ‘Charcoal ironmaking in 19th-century Shropshire’, Economic History Review, 61(1) (2008), pp. 80-98. The existence of the industry described there was completely ignored by this author in 2005.
  • The list of bloomery forges is likely to be deficient, as more continue to be discovered. It is not inconceivable that their output in the early 16th century was 50 per cent higher or even double what this author estimated in 2005. However, as he suggested that English output was only a modest proportion of English consumption, the effect on the consumption estimate (though significant) will not be great.