Understanding the Database

Visualizing Abolition’s database allows users to map the suppression of the African slave trade by examining records of letters exchanged between the British Foreign Office and British commissioners, ministers, naval officers, and representatives of foreign governments around the world during the nineteenth century. It provides them access to important data such as the names of senders and recipients, places of origins and destination, dates, as well as the subject of the letters when available. It does not provide access to copies of the actual letters.

The database has 30,963 records of letters. We will never know how many letters were actually exchanged, but we listed all that we found in our sources, which may very well comprise the majority swapped at the time with the British Foreign Office. Users may view the flow of the correspondence exchanged by searching the database, filtering the information available, and plotting it on a timeline, world map, or network graph. They may also download the whole database, or just the information they desire, as a CSV or JSON file, which they can later import and examine using their favorite statistical software, such as Excel, SPSS, and STATA.

Although the database favors a quantitative approach, it also allows users to get an idea of the letters’ content by providing them with a summary of their subject when available. Users may obtain copies of the letters by following the sources listed in the database. Moreover, the database is supplemented by essays on the history of British abolitionism and the suppression of the traffic as well as a gallery of images contemporary to the campaign divided into four categories: documents, people, places, and ships. The essays and the gallery of images provide additional context to the information available in the database.

Nature of the Sources

The Foreign Office Slave Trade Series of the British Parliamentary Papers makes the thrust of Visualizing Abolition’s database. Created in the context of the campaign, the series emerged as a way for the Parliament to publicize its efforts in suppressing the traffic and informing the public about the campaign’s progress. Despite the potential for political propaganda or deceit, important factors indicate that the correspondence published is relatively complete and authentic. First, notwithstanding British attitudes toward Africans and others, a large segment of the population of the time genuinely viewed slavery and the slave trade as immoral and unjust practices. Second, the Parliament published the letters in full or extracts periodically, usually one to two years after receipt or dispatch. Finally, the correspondence published also contains letters showing evidence of British subjects, including bureaucrats and navy officers, involved directly or indirectly in the traffic.

Since the original “Blue Books,” the British Parliamentary Papers were reprinted in several formats, such as ledgers, microfilms, and more recently electronic files, by several publishers and companies, such as the Irish University Press and ProQuest, a global information-content and technology company. Several libraries around the world have copies of the papers in one or more format. Thus, to help users locate the letters recorded in the database, they appear listed after the conventional, short notation attributed to the British Parliamentary Papers. W. Pennell’s letter to the Earl of Aberdeen, dated from Rio de Janeiro, 18 December 1830, for example, is listed as BPP, 1831-32 (010), XLVII, 112, where “1831-32” refers to the year of the session; “(010),” the paper number; “XLVII,” the session’s volume number; and “112,” the page where the letter is located. Sometimes the paper numbers are given in square brackets. This is particularly the case of Command Papers, as opposed to the usual Sessional Papers, simply because they were published “by command of Her Majesty.” In any case, this notation will help users to retrieve the desired correspondence from any version of the British Parliamentary Papers.

Data and Variables

Visualizing Abolition’s database is made of data collected directly from the sources previously mentioned. Below is an image of a typical letter exchanged between British commissioners and the Foreign Office. It lists the names of the sender and the recipient, the letter’s place of origin, and its date. Sometimes the sources also provided the letters’ destination, date received, and their subject. We collected all these data and stored them in variables labeled accordingly, that is, “Name of sender,” “Name of recipient,” “Date sent,” Date received,” “Place of origin,” “Place of destination,” and “Subject.” To these variables, we added two more, “Unique identification number” or “ID” of the letter and “Sources.”

Given the huge amount of information, and considering that the British were frequently interacting with non-English speaking societies, the spelling of several terms varied significantly. We took the liberty, therefore, of standardizing place names so users could immediately search for them in our website and our database could return their search results appropriately. Because our research team speaks American English, we also decided to adjust terms like “colour,” “labour,” and “neighbourhood” to the American spelling. Finally, some letters, especially those authored by British navy officers at sea, gave a set of geographic coordinates as their place of origin. We accepted that information and used it to plot the letters on our map viewer, labeling the letters’ origin after the name of the ship in which they were composed.

Geographic Coverage and Distribution

One can see through the mapping of correspondence origins the evolution of centers engaged in suppression. The size of its marker augments as more letters are sent from that location for a year, and over time the size and location of these markers generally follow new export and import sites for African slave labor. In the span of the campaign, the sites most active in terms of correspondence collected by the Foreign Office are London, Freetown, Rio de Janeiro, Havana, Paris, Zanzibar, Lisbon, and Madrid.
The correspondence available in the Slave Trade Series begins in 1817. By then, Britain signed treaties with Portugal and Spain limiting their slave trafficking to centers south of the equator. By 1830, Brazil and Spain both agreed to enact abolition; the next year brought Brazil to declare free all slaves entering Brazil from abroad. At this time we see fewer letters exchanged in the timeline chart. Slave trafficking to the Caribbean and South America certainly endured, especially given the European demand for slave-produce. Correspondence in the mid- and late-1830s increase in tandem with this challenge. Courts around the Atlantic were established as early as 1819 in Freetown, Rio de Janeiro, Havana, and Surinam to adjudicate ships and crews accused of trafficking enslaved Africans, via evidence of the enslaved on board or simply the presence of materials including shackles, barricades, and large stores of water. Sites of later courts included Kingston, Luanda, St. Helena, the Cape, and others; these sites all have a substantial presence in the Slave Trade Series. Early courts were designed to be “mixed-commision,” where representatives of both British and the respective national authority based on the court’s location adjudicated ship captures, awarded prizes, and registered liberated slaves who remained displaced.

By the 1840s, many new sites appear on the maps as compared to earlier decades. This trend is also evident in our timeline figures, where the overall peak of correspondence occurs. By zooming into the map, viewers can see the coordinates of certain ships in the West African Squadron from where agents report their captures or inactivity. The 1840s appear to be the point when the full effects of the naval blockade on the western coast of Africa were felt. There also appears a pattern of intense diplomacy throughout Europe during this decade. For the 1850s, the correspondence sites are still concentrated in West Africa, while spreading into the Middle East, North and Southeast Africa, and the Indian Ocean especially by the following decade and into the 1870s. Less-recognized centers of the campaign also become visible including Cairo, Luanda, Constantinople as the Foreign Office referred to Istanbul in the letters, Washington D.C., and others as do areas apparently on the margins of the paper trail, though they were still involved in the global network. Locations with limited involvement include Aleppo, Lamu, Manilla, and Dresden.

The steep decline in correspondence in the mid-40s may reflect the consequences of the Palmerston (1839) and Aberdeen Acts (1845) when Britain could engage in suppression with fewer checks. A later decline in letters in the timeline chart after the early 1850s follows Brazil’s abolition of its trade; Cuba remained a large importer until its abolition in 1867, before which the slave traffic to Havana doubled in relation to Voyages figures for the 1840s. This can be explained by the absence of the Brazilian market; still Brazil did not terminate slavery until 1888. Many of the letters in and after the 1860s were sent from Zanzibar and centers related to the slave trafficking from the east coast of Africa to ports in India, the Persian Gulf, the Arabian Peninsula, and Indian Ocean islands of Mauritius, Réunion, and Seychelles. This traffic was far smaller than its Atlantic counterpart, though heavily covered in contemporary issues of the Illustrated London News. Eventually correspondence in the Slave Trade Series diminishes, following the global trend of accepting abolition through means of national determination, industries finding new means of cheap labor, or Britain’s colonial will in the following period of formal imperialism throughout Africa and Asia.

Other Projects

Visualizing Abolition was modeled after a number of successful projects. Below is a short list of some projects that served us as a source of inspiration. Not everyone is related to the history of abolition or the African slave trade.