Visualizing networks and careers

We mostly post map visualizations of our historical data on sailors, but we’re working on other visualizations to gain insight into our data as well.

Markov models

We’ve teamed up with DHLab and Marijn Koolen (@marijnkoolen) of the KNAW-Humanities Cluster to do a thorough analysis of sailor’s careers. As a first step, Marijn produced Markov model visualization of all steps in the career data we reconstructed from the digitized VOC pay ledgers. These visualizations give very good insight into the data. The one pictured below, for example, shows the various ranks from which crew members were promoted to ‘skipper or master’ and the most frequent career steps after having served as a ‘skipper or master’ on a Dutch East Indiaman (most often: ‘end of VOC career’). It also suggests that senior boatswains always climbed up in the hierarchy to become a skipper. This is a remarkable fact, even though we have only four senior boatswains in our career clusters. Thanks to this visualization, we now know that we need to look into our data again to find out whether senior boatswains were indeed without exception very highly skilled, or that something is wrong with these clusters.

Markov model showing careers steps to and from ‘skipper or master’
Markov model showing careers steps to and from ‘skipper or master’

Network visualizations

We’re also working together with Veruska Zamborlini and Al Idrissou. They are experts on automated methods for linking entities from various datasets and subsequently validating the links. We did a pilot on our VOC career data to see if we could devise a way to automatically validate our career reconstructions, which consist of multiple observations from the digitized VOC pay ledgers: is our clustering correct, or did we sometimes wrongly link observations to one individual?

We experimented with networks around captains. They were the highest officials on board and had a significant say in the hiring of crew members. Our hypothesis was that it is likely that a captain would hire sailors that he’d sailed with on an earlier voyage to the East Indies, and that these recurring patterns would help us to validate clusters. Veruska and Al produced network visualizations like the one pictured below. So far, alas, evidence from the network analysis is too sketchy. But the experiment has inspired us to test other crew network hypotheses, so there’s more on this to come.

Recurring captain-sailor relations in Jacob Onkruijt’s network
Recurring captain-sailor relations in Jacob Onkruijt’s network

Daniel Engel: a maritime career reconstructed

Daniel Engel was a young man from ‘Dantsig’ (modern-day Gdańsk in Poland) who travelled to the Dutch Republic in the mid-18th century to apply for a job with the Dutch East India Company (VOC). We’ve written about him before (in this blog post, where we introduced the Company’s pay ledgers, one of our main data sources) and now come back to him once more. Not that Engel is so special–on the contrary, there were thousands of men like him in the ranks of the VOC–but because his story is a good case in point for illustrating our work on reconstructing maritime careers.

1766: first journey to the East Indies
Entry Daniel Engel in VOC pay ledger (1766)
Entry of Daniel Engel in the pay ledger of Dutch East Indiaman Vrouwe Anthoinetta Koenrardina (1766)

A clerk of the Delft chamber of the VOC recorded Engel’s name and birthplace in the pay ledger of a brand new ship called Vrouwe Anthoinetta Koenrardina, that would set sail for the East Indies on 1 October 1766. The VOC hired Engel as a common sailor, on a wage of seven guilders per month. This is all we can infer about the life of Daniel Engel from his employment record, but we do know more about the environment in which he would work en route to Asia. There were 300 men on board, mostly Dutchmen, as can be seen from the map below, but also quite a few men from the German lands and the Southern Netherlands, as well as a number of individuals from the coastal areas of southern Scandinavia, Malta and Batavia (modern-day Jakarta).

Birthplaces of the crew members of the 1766 journey to the East Indies of VOC ship Vrouwe Anthoinetta Koenrardina. Blue markers: sailors and maritime officers. Green markers: military personnel. Visualisation: Triply

This is an interactive map; clicking on a marker reveals employment details of a crew member. By default, the map only shows one marker per geographic location, and the Gdańsk marker is not linked to Daniel Engel. By clicking on the expand button (^) located just above the map, and changing the map setting to ‘Grouped’, it becomes visible that Engel was joined on board by one other man from his home town: Christiaan Cornelis Gerlach, who was employed as a soldier. While Engel returned to Europe on the same ship in 1768, Gerlach stayed behind in Asia, where he died on 3 August 1770.

Interrogated by the English

More than ten years later, in 1781, shortly after the beginning of the Fourth Anglo-Dutch War, a Daniel Engel from ‘Dantzick’ was taken to the Fountain Tavern in Plymouth to be interrogated after his ship had been captured by the English privateer ship Defiance (see this blog post for more on privateering during wartime). He told his questioners that he was 28 years old, worked as a boatswain on a vessel called De Keyser Josephus, and that he had lived in Rotterdam for the past thirteen years. It is likely that this Daniel Engel is the same person as the one who sailed to Asia in 1766, even though he would have been only thirteen or fourteen years old back then. He had switched to the merchant marine: De Keyser Josephus was en route from Curacao to Rotterdam, carrying a cargo of wood, hides, sugar, tobacco, cocoa, coffee and tea.

Report of interrogation of Daniel Engel. National Archives, HCA 32/383-1. Courtesy Brill.
To Asia again

It seems Daniel Engel switched back to the ranks of the VOC in the late 1780s: there are mentions of a Daniel Engel from Dantzig in VOC pay ledgers from 1788 and 1792. While he worked as a boatswain’s mate on his second voyage to the East Indies and back (he returned in the Dutch Republic in 1791), he was an able seamen on his third, from which he did not come back: Engel died in Asia, on 2 October 1798, when the VOC was already in a state of bankruptcy.

Daniel Engel did not rise high through the ranks of the VOC and the merchant marine–he died as an able seamen. By zooming out from Engel, and reconstructing careers of many more sailors, our future research will point out whether it is likely that he lacked the skills to get promoted or changing labour market conditions were to blame.

Newspaper article

Daniel Engel also featured in an article on the Dutch Prize Papers project in Dutch national newspaper Trouw!

How do we reconstruct sailors’ careers?

We published a paper on our methodology of reconstructing sailors’ careers in the HUMIGEC project. It’s called ‘Small Lives, Big Meanings. Expanding the Scope of Biographical Data through Entity Linkage and Disambiguation’ and was co-authored by Lodewijk Petram, Jelle van Lottum, Rutger van Koert, and Sebastiaan Derks.

The paper was originally presented at the 2017 edition of the Biographical Data in a Digital World conference, held in Linz, Austria. The maritime dataset and career reconstruction methodology serve as a use case to introduce the Huygens ING digital biographical data policy.