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Stephen Gadd @docuracy.co.uk · 19/05/2026

For sea-router calibration: 513 dated voyages from the Datini/Melis corpus (1379–1492) across galleys, carracks, brigantines and more. e.g. Venice → Mallorca, departing in a cog 19 Jun 1396: the router predicts 29 days, the source records 37. bsky.app/profile/did:...

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Stephen Gadd @docuracy.co.uk · 19/05/2026

Companion to the Datini Letters map: a new Voyages explorer for the Melis archive. 3,393 Mediterranean ship records (1379–1492). Arcs coloured by predominant vessel type per route. Ports geocoded via @whgazetteer.org. docuracy.github.io/datini/viagg... #DigitalHumanities #DH #MedievalMed

Map of the Mediterranean and adjacent waters on a dark basemap, showing 3,393 ship voyages from the Melis archive (1379–1492) as curved arcs between origin and destination ports. Arc colour encodes the predominant vessel type on each route: red for galleys (galea, galeotta, fusta, saettia), purple for cogs and carracks, gold for general sailing ships (nave, navetta, panfilo), teal for Mediterranean coastal traders (liuto, rampino, vacchetta), magenta for brigantines and pinnaces, sky-blue for boats and small craft, muted purple for unspecified types. Arc width scales to voyage count per route. The densest threads cluster across the western Mediterranean between Italy, Catalonia and the Balearics, with prominent reaches out to North Africa, the Aegean, the English Channel and the Atlantic. A left-hand sidebar lists filters — dated-only toggle, year range, vessel-type chips colour-matched to the map — and a legend giving each category's example types.

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Stephen Gadd @docuracy.co.uk · 18/05/2026

Try a "Starts with" search for "smuggler" here: 36 results in GB c.1900 (excludes N.I.). You can download results as CSV or GeoJSON and use GIS tools to find those >3 mile inland. maps.nls.uk/projects/os1...

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Stephen Gadd @docuracy.co.uk · 13/05/2026

Calculations of coastal visibility and meteorological attenuation are used together with hull and sail profiles, and seasonal wind, wave, and current data in this online tool for computing plausible ancient sea routes: github.com/docuracy/His...

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Stephen Gadd @docuracy.co.uk · 10/05/2026

🔔 A heavy church bell meant a heavy cart and a way capable of bearing it. Can the spread of bells >5cwt from their foundries serve as a proxy for pre-modern wheeled-transport networks, at least where navigable waterways can be ruled out? 1/5 #HistoricalGIS #EconomicHistory #TransportHistory

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Stephen Gadd @docuracy.co.uk · 04/05/2026

New in the Datini Letters explorer: click any city to focus on its correspondence routes. Shareable links capture the full state of the view. docuracy.github.io/datini/#mode... #MedievalSky #DigitalHumanities

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Stephen Gadd @docuracy.co.uk · 01/05/2026

✉️ Explore 145,000 medieval merchant letters as a live map: the correspondence network of Francesco di Marco Datini (c.1363–1412), spanning Florence to Barcelona to North Africa. Visualise routes, travel times & seasonality. docuracy.github.io/datini/ #DigitalHumanities #MedievalHistory

A dark-themed interactive map of the medieval western Mediterranean showing 14th-century merchant letter routes as curved arcs coloured from cyan (fast, 0–5 days) through yellow to red (30+ days). Short land routes between Tuscan cities glow cyan; longer sea routes to Barcelona and Majorca burn orange and red, revealing the unpredictability of medieval maritime travel.
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Long (accessible description for screen readers / figure caption):
Screenshot of the Datini Letters Geospatial Explorer in Travel Time mode. A dark basemap of the western Mediterranean is overlaid with curved arc lines connecting pairs of cities in the Datini merchant network. Arc colour encodes average letter delivery time on a gradient from cyan (near-instant, 0–5 days) through green and yellow (one to two weeks) to orange and deep red-magenta (more than 30 days). Dense clusters of fast cyan arcs radiate from Florence and Pisa across Tuscany, reflecting the reliable day-or-two land post. Arcs reaching westward to Barcelona, Valencia, and Palma de Majorca shift to orange and red, capturing the slower and far more variable sea routes that could take anywhere from a week to several months. City nodes are shown as circles: pink for the main Datini fondacos (Pisa, Florence, Barcelona, Genoa, Valencia, Majorca) and blue for correspondent cities. A sidebar on the left shows the Travel Time mode is selected, with a cyan-to-red colour legend and a filter slider for minimum letters per route.

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Stephen Gadd @docuracy.co.uk · 11/03/2026

Medieval Markets & Fairs in England & Wales: remember the excellent dataset published back in 2003? I've given it a snazzy new interface, incorporating various updates which were made following publication. Separately, I'm working on extending it to 1846... ihr-digital.github.io/markets-and-...

Image showing the new interface for the 2003 Medieval Markets & Fairs dataset.

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Stephen Gadd @docuracy.co.uk · 02/08/2025

Sounds amazing! I'm curious to see how closely the cross-Channel route and timing match this 4-or-5-day wind-and-current-based prediction from docuracy.github.io/Historical_S...

Predicted optimum route from Honfleur to London for a knarr sailing in August.

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Stephen Gadd @docuracy.co.uk · 19/07/2025

Hours of fun spent realigning my foolishly London-centric assumptions about medieval European trading networks. Shetland, for example, was far from peripheral: a non-Mercator map-projection helps. I've rebuilt the journey-timed, square-rigged sailing algorithm for docuracy.github.io/Historical_S...

Map of northern and western Europe showing computed square-rigged sailing routes between the Baltic Sea and Spain. Outward journeys curve northwest via Shetland and the North Atlantic, while return journeys favour the English Channel. This asymmetry arises from prevailing winds, currents, and the hydrodynamic limits of medieval sailing vessels. A spherical (non-Mercator) projection is used, better reflecting great-circle geometry and the true spatial relationship of regions such as Scandinavia, Shetland, and Iberia.

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Stephen Gadd @docuracy.co.uk · 18/07/2025

That's not what I see. Apply those unemployment rates to mid-career wages and it's evident that humanities are not a "safe financial bet". The situation is even worse when you factor in underemployment and investment in graduate degrees.

Data table showing labor market outcomes for select college majors including Computer Science, Engineering, Graphic Design, English, History, and Philosophy, detailing their unemployment and underemployment rates, early and mid-career median wages, and the financial impact of unemployment and underemployment on mid-career earnings.

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Stephen Gadd @docuracy.co.uk · 05/07/2025

🌍 Ports are now (optionally) shown on the eRutter to help with route picking. 🤔 They're currently fetched from @wikidatacommunity.bsky.social, but this would be a great use case for a @whgazetteer.org temporal API to filter out modern ports and highlight ancient ones.

At low zoom levels, cluster markers indicate the locations of ports.

At higher zoom levels, each port gets its own marker, coloured by category.

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Stephen Gadd @docuracy.co.uk · 04/07/2025

... 📖 All of the code for extending coverage can be found together with an outline of the methodology at github.com/docuracy/His.... [3/3]

The grid of H3 cells at blended resolutions strikes a balance between detail and responsiveness.

A grid of H3 cells over land facilitates computation of the visibility of features out at sea.

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Stephen Gadd @docuracy.co.uk · 04/07/2025

... 📱It works better on mobile devices now too, using Mercator projection instead of globe, and with an initially-minimised Options panel. The routes and all parameters used can be exported for use in other GIS applications. [2/3]

Screenshot showing mobile optimisations: Mercator map projection, and initially-closed Options panel.

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Stephen Gadd @docuracy.co.uk · 04/07/2025

🪄Historical Sea Routing is now much quicker to load, reload, and compute seasonally-plausible sailing routes, thanks to some behind-the-scenes browser magic. Find a 6500-mile return trip in under 1 second! 🛟 Do you have historical voyage data which might help with calibration? [1/3]

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Stephen Gadd @docuracy.co.uk · 29/06/2025

... Time of year makes a big difference too. Monthly-weighted graphs are switched and new routes computed in less than half a second, all within the browser.

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Stephen Gadd @docuracy.co.uk · 29/06/2025

... I need yet to tune the weighting of various parameters, but it’s striking how the same principles that shaped trans-Atlantic triangular trade routes in the age of sail apply on a more local scale too: prevailing winds, swell, waves, and currents all make return routes diverge from outbound ones.

In September, the least-cost path from the west of Ireland to the east of England tracks around the north of Scotland. This indirect path reflects prevailing winds, currents, and swell patterns that favour northerly routing during this month, despite the longer distance.

... whereas the least-cost path from the east of England to the west of Ireland tracks through the English Channel. This asymmetry highlights how environmental factors such as wind direction, wave conditions, and current flow make the return journey optimally follow a very different path.

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Stephen Gadd @docuracy.co.uk · 28/06/2025

... 🌊Each cell now has bathymetry and DEM-based clear-weather land-visibility data; also month-wise indicators of hourly-average wind, waves, surface current, and nocturnal+meteorological attenuation of visibility. Thanks to @viabundus.bsky.social and @alexislitvine.bsky.social for inspiration!

Chart of route-graph cells indicating clear-weather land-visibility and sea-depth<15m

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Stephen Gadd @docuracy.co.uk · 17/06/2025

... using this graph of interconnected H3 (Hexagonal Hierarchical Geospatial Index) cells, I've computed and plotted a speculative historical sea route from Kilcolgan Castle to Faxfleet in under 2 seconds, all running in the browser. No server infrastructure or internet connection needed! ⛵

Map showing speculative computed historical sea route, favouring coastal sailing.

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Stephen Gadd @docuracy.co.uk · 16/06/2025

🧭 Building a lightweight sea-routing graph for historical GIS & DH use cases beyond simple port-to-port hops. Edges are weighted for ~5km coastal preference. Aiming for serverless exploration of connectivity in historical maritime trade. ⚓️ #MaritimeHistory #HistoricalGIS #DigitalHumanities

Diagram of historical sea routing graph for Europe.

Diagram of historical sea routing graph for Europe, showing (in red) weighted edges in the zone favoured for coastal sailing (~5km).

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Stephen Gadd @docuracy.co.uk · 30/04/2025

... although it picks out the Great Eastern lines very clearly.

Map showing Great Easter railway lines in the vicinity of London c.1900

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Stephen Gadd @docuracy.co.uk · 30/03/2025

👇Results from my latest version of desCartes, a hybrid machine learning system for detecting roads on old maps. Its 0.76 IoU score for roads is 31% better than the closest benchmark. 🤯 Preprint forthcoming on arXiv.

The robustness of the desCartes Ilastik-Segformer-b4 model's road segmentation is illustrated in these images, which demonstrate accurate discrimination between main roads (red), minor roads (green), semi-enclosed paths (orange), and unenclosed paths (yellow) in diverse urban and rural environments.

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Stephen Gadd @docuracy.co.uk · 28/03/2025

Here it is on @layersoflondon.bsky.social in 1746, where you can also find an overlay of Strype's maps for 1694-1720. The area isn't labelled on those, though. www.layersoflondon.org/map/overlays...

Detail from John Rocque's 1746 map of London, Westminster & Southwark, indicating St Agnes le Clare.

Modern map overlaid with detail from John Rocque's 1746 map of London, Westminster & Southwark, indicating St Agnes le Clare.

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Stephen Gadd @docuracy.co.uk · 04/01/2025

Inventor Alexander Lagerman's beautiful machines in the Matchstick Museum (Tändstickmuseet), Jönköping, including a fairly early (1892) industrial example of non-circular gears. 👌🏻 sv.m.wikipedia.org/wiki/Alexand...

Detail of Alexander Lagerman's "complete machine" for making matches.

Non-circular gears. Detail of Alexander Lagerman's "complete machine" for making matches.

Detail of Alexander Lagerman's machine for making matchboxes.

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Stephen Gadd @docuracy.co.uk · 21/12/2024

Very nice, but there was an earlier pier as shown here in 1872 [www.jp137.com/day/6294.jpg]. Bournemouth Local History page on Facebook is a great resource with photos and possibly some of Birch's plans [www.facebook.com/profile/1000693625…].

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Stephen Gadd @docuracy.co.uk · 22/02/2024

... well, this is a fascinating catalogue of (among other things) watermarks: www.memoryofpaper.eu/BernsteinPor... It led me to what looks like a very close match dated 1752 here: www.academiacolecciones.com/dibujos/inve...

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Stephen Gadd @docuracy.co.uk · 21/02/2024

Help, please? I'm trying to date a ledger by its watermarks and ruled lines (see attached). Does anyone here know how the Villedary marks changed over their long period of production?

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Stephen Gadd @docuracy.co.uk · 12/02/2024

... the map can now show which ports had a Legal Quay. My 2017 article explores how the lack of a Legal Quay (for import and export of goods) tended to suppress coastal trade too: ehs.org.uk/article/ille... docuracy.github.io/Elizabethan_...

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Stephen Gadd @docuracy.co.uk · 12/02/2024

...fixed the map links so that you can now read the corresponding transcripts without having to download the entire dataset.

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Stephen Gadd @docuracy.co.uk · 12/02/2024

I've finally got round to publishing the geolocated transcripts I made of several Elizabethan Coastal Surveys (1565). Primarily for "suppressing pirates and other disorders" and for Customs regulation, they include details of local populations and vessels. github.com/docuracy/Eli...

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Stephen Gadd @docuracy.co.uk · 20/01/2024

Drop something yellow? How about this beauty from the Boboli Gardens? www.uffizi.it/en/artworks/...

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