Sample charts of data on the tonnage and shipping of Ireland, by port, 1719–1764

I’ve updated content for the CUSTOMS15 18th century Irish trade project, which is joint work between Patrick A Walsh, Eoin Magennis, and myself, with:

This is our first real cut at getting trade-related data at the port , rather than national, level. Even though it is work-in-progress, a little background  to the work is appropriate, well in advance of a fully documented dataset.

The core trade data in the sources, i.e., detailed quantities and values of commodities imported and exported, are each year typically supplemented by tables with trade-related information. Each of the annual ledgers seem to have a one-page table on the tonnage and shipping of Ireland. These tables are so well and consistently structured, that their essence can be grasped fairly immediately. Click to zoom in on the image:

Image of tonnage and shipping table from Customs 15 ledgers (UK National Archives) Vol. 17 (for the year ended 25th March 1714)

300 years old, useful, and beautiful: the tonnage and shipping table from the Customs 15 ledgers from the UK National Archives, Vol. 17 (for the year ended 25th March 1714).

We see, for any given year, the number of ships in total, the number of ships for each port, tonnage also at national and port level, with tonnage distinguished further by (what we take to be) the country or region of origin of the owners of shipping. The numbers are uncomplicated, in being in either units of ‘ships’ or ‘tons’ (with the occasional fraction of a ton). So, data-entry is fairly easy. Tonnage data is totalled across rows and down columns, which makes data-checking straightforward too.

These data relate to international trade, rather than including trade between Irish ports, i.e., the ‘coastways trade’.

This image above is based on scans we ordered from the UK National Archives. We did that for 12 full volumes out of 140 in the total Customs 15 series (1 for the year 1698, and 1 volume at each of the 11 ten-year intervals from 1704 to 1804). The  tables in these sample volumes looked so open to data capture that we decided to get photographs ourselves for a continuous sequence of years in other volumes, giving us a run of data from 1719 to 1764, to get a ‘quick win’ dataset.

Patrick Walsh did the needful, time-consuming, and hard work of photography, and we’ve got that data into Excel, and then into MySQL to make it easier to interrogate and present in different ways.

Here’s how one slice of the tonnage data (part of that 1719) looks in MySQL, via the Navicat interface.

Screenshot of MySQL tonnage table.

A slice of data, for 1719, from the tonnage tables, as seen in MySQL, via the Navicat interface.

This is best explored interactively via the page I’ve set up with links to charts.

In those charts, you can zoom in and out for particular time periods, and show or hide particular series, to get an initial feel for the data. So, off you go!

We already see one or two interesting things which may be fairly easily explained with a little more background work on the existing literature on the 18th century Irish economy and trade, and with our own cross-checking against the core trade data, when we can get to capture all of it.

One feature is the spike in tonnage associated with Dublin  port in the year ended March 25th 1723:

Chart of tonnage by port regions, showing Dublin spike.

The spike in Dublin tonnage in 1723

This doesn’t appear to be an error in the originals—the totals add up on the original table, at least. I’m unsure what it reflects. Perhaps a spike in coal or grain imports?

Also intriguing is the drop from 1740 to 1750 of tonnage recorded as Irish, along with a drop in French tonnage around the same time.

Chart of origin of tonnage, showing all but Britain.

British tonnage dominates: but stripping it out reveals swapping between different origins between 1740 and 1750.


There’s an eventual rebound in the Irish number, but during the decade the falls are made up by tonnage recorded as from the Baltic, Holland & Flanders, and the Plantations (British America), at least for a while.

Presumably this is war-related, but the precise ‘swapping’ between different regions, to give a broadly unchanged total, is more interesting than an ‘across-the-board’ fall. Perhaps it reflects shifting wartime alliances and/or varying embargoes over the period, leading to this shuffling of apparent ship ownership?

In the volume for the year ended 1763, the clerks  explain why the French tonnage numbers are low around in that year. Nothing, if not succinct:

Image of part of 1763 tonnage table, showing table entry 'War'

This ‘war’ cell is in the French tonnage column—and the Dublin port row, in this 1763 tonnage spreadsheet.

Comments, suggestions, expressions of interest, etc. on this work-in-progress are most welcome, here, or to