The Slaving Voyages KML in GoogleMaps

GoogleMaps can also be used directly, without using Map Engine Lite to upload a spreadsheet for each layer. To create a map of the slaving voyages for the second half of the eighteenth century, go to GoogleMaps, select My Places, and then Create Map. Next, either upload the compressed KML file (KMZ)  generated with GoogleMaps (see previous post) or enter the URL for its location on GoogleSites. It, in theory, is then rendered over the default GoogleMaps content such as Wikipedia and photo links. The base map can also be changed to the  satellite or GoogleEarth view within GoogleMaps, but the time slider is not enabled.

In practice, the KML file uploads but does not render the voyages all at once or in chronological order. The voyages display in twenty-five separate "layers." By opening the map in GoogleMaps by clicking the link below the embeded version, users can advance through the layers with the index at the foot of the panel that displays daily position symbols, dates, and TSTD links.

View The Slaving Voyages KML in GoogleMaps in a larger map

Opening the Web map with GoogleMaps also allows users to save it to their own My Places and modify it in various ways such as adding the commonly used place markers or pushpins as well as lines and polygons or descriptive attributes in pop ups.

Time Enabled Slaving Voyages on GoogleEarth

GoogleEarth provides another free option for publishing Web maps, one that provides an alternative to videos for sharing the temporal function of ArcMap. GoogleEarth 7 can be downloaded gratis here. It is an application that runs on and saves your data to your computer, not the cloud.

I created the below temporal Web map of the British and Dutch slaving voyages by converting the ArcMap GIS file (MXD file) into a KMZ file (a compressed KML file) using the Map to KML Tool found with the other Conversion Tools. GoogleEarth and other Web mapping applications use KML (Keyhole Markup Language) to render point, line, and other types of features. That KMZ file therefore includes not only the features and their attributes but the way I symbolized and otherwise configured them as layers in ArcMap.

Next, I opened the KMZ file with GoogleEarth and configured the time slider settings and symbols to suit GoogleEarth, a rather different type of display than ArcMap. Then I saved the reconfigured layer as one of My Places in GoogleEarth as well as, by right clicking the layer folder, as a new KMZ file. I uploaded that KMZ file to a website that I created on GoogleSites, for free yet again, storing it in a page created with the File Cabinet Template and setting its permissions to allow public access. Then I went back to Google Earth and opened the Embed KML Gadget, configuring the various options such as dimensions and entering the URL for the KMX file stored on my GoogleSite.

The result is a fully functional temporal GIS of the British and Dutch slaving voyages of 1751-1795, first shared using ArcGIS Online. Selecting any of the daily position symbols opens a pop-up box with a link to the Web page for that voyage in the Trans-Atlantic Slave Trade Database. By adjusting the various controls of the time slider, users can view the entire period (1751-1795) or constrain it to a single decade, adjust how many months or years of symbols are visible at once, and move along the temporal sequence one step at a time or as a continous animation.

The control of the time slider, especially over the speed at which the sequence runs, is limited compared to using it in GoogleEarth. The KMZ file can, however, be downloaded and added to GoogleEarth running on a computer or added using the Add Network Link. Doing that will also allow users to access the individual layers for each voyage, the daily position points, and all the attributes as well as to resymbolize points, remove and add data, such as place markers for ports, and finally to save their work as a new KMZ file.

The free versions of GoogleEarth, ArcGIS Online, and GoogleMaps Engine Lite, of course, cannot do nearly as much as the ones you pay for: GoogleEarth Pro is $399 for an annual license; a paid subscription to ArcGIS Online is at $2,500 per year for the minimum of 5 users; and GoogleMaps Engine is "expensive."

Seasonality of the Slave Trade Voyages, 1751-1795

A temporal analysis in ArcMap of the slaving voyages in the database yields the following temporal vizualization. Forty-six of the forty-eight voyages are Dutch and two British, most of them transporting enslaved people across the Atlantic from Africa to Suriname and the Caribbean. Forty-four of the voyages also appear in the Trans-Atlantic Slave Trade Database. For further details on the voyages, see this post.

I achieved the visualization by changing the year of each voyage to a single year, setting both the time interval and time window to one week, and creating a new point feature in the South Atlantic labeled with the month field. The daily-position symbols are triangles, with a week’s worth showing at a time. Their colors represent the direction of the voyage segment, based on their destination fields: green for northbound, orange for southbound, and purple for westbound. That compresses the voyages, which took place from 1751 through 1795, into a single annual period and allows analysis of variation by week and month.

The Trans-Atlantic Slave Trade Database contains many more voyages than this GIS and therefore reveals a great deal of variation in seasonal patterns and why it occurred, as explained in this essay.

Websites with Info on Vessels

These are some useful Websites with information and images about specific sailing vessels:

1. Maritiem Digitaal: www.maritiemdigitaal.nl
2. Sailing Ships: www.sailing-ships.oktett.net
3. The Ships List: www.theshipslist.com
4. Three Decks - Warships in the Age of Sail: www.threedecks.org

Side-By-Side Comparisons

I said my next post would be methodological: how I carried out the project, why I made choices I did, and so on. But in the meantime I want to post this web application that allows you to make side-by-side comparisons of the map of slaving voyages.

Atlantic Slave Trade Voyages, 1751-1795

The first aspect of the ACLS project that I am publishing relates to the Atlantic slave trade.

I decided to share it first because of its close relationship to the online digital humanities project I used the most for my research on the role of people of African origin in establishing open-range cattle ranching in the Americas (see my 2012 book, Black Ranching Frontiers), namely the Trans-Atlantic Slave Trade Database. That digital humanities project produces summary and customizable tables, statistics, and graphs regarding the transport of some 12.5 million enslaved Africans across the Atlantic Ocean over the sixteenth through nineteenth centuries, but it produces maps only of the embarkation and disembarkation ports for the some 35,000 voyages.

In contrast to the the Trans-Atlantic Slave Trade Database, the GIS posted below produces maps of the routes of forty-eight slaving voyages during the second half of the eighteenth century. The daily, noontime vessel position and other data come from the Climatological Database for the World's Oceans, 1750-1850 (CLIWOC), a project that assembled maritime weather observations from logbooks in archives in Britain, the Netherlands, and Spain. Forty-six of the forty-eight voyages are Dutch and two British, most of them transporting enslaved people across the Atlantic from Africa to Suriname and the Caribbean. Forty-four of the voyages also appear in the Trans-Atlantic Slave Trade Database, and clicking any of their daily position markers pops up a box with a link ("More info") to the relevant record in that database (the other four voyages concern vessels that carried slaves on voyages that were not trans-Atlantic). The box also contains date and cargo information as well as, in some cases, an image of the vessel. Clicking the route line of a voyage brings up a box with the vessel name and, in some cases, a description of arrivals, departures, and cargoes from the shipping news sections of newspapers. You can also click on place markers for the archives in Europe that preserve the logbooks, ports along the African coast and in the Caribbean, and so on to bring up images and links to further information about those places.

The GIS thereby facilitates novel visualizations of the slave trade, allowing users to better appreciate the horror of this monumental forced migration. For example, the map layers that show the patterns of death among the enslaved and disposal of their corpses overboard during the Middle Passage from Africa to the Americas help to visualize that aspect of the slave trade. One uses proportional point symbols to convey the number of deaths on a particular day at a particular position in the Atlantic. Another displays the density of deaths and disposals across the entire Middle Passage.

I hope you enjoy the GIS (despite the heinous topic), provide feedback, suggest collaborations, and feel free to use the data and programming to produce non-commercial derivative products.You can modify the GIS and save a new version by opening it in either the  free ArcGIS Online map viewer or in ArcMap 10 if you have it installed on your computer. Simply click on the "View Larger Map" link just below the map.

The GIS and blog are © 2013 but open source and licensed through the Creative Commons as attribution-noncommercial 3.0. The logbook data that the GIS maps ultimately derive from archival transcriptions carried out in British and Dutch archives by the CLIWOC project team members, who state that the “aim of the project is to produce and make freely available for the scientific community the world’s first daily oceanic climatological database” (www.ucm.es/info/cliwoc/intro.htm). The CLIWOC 2.1 MS Access database, which you can download from the CLIWOC website, includes fields that identify the archive, document number, and the CLIWOC team member who transcribed the logbook for each of the voyages. Anyone is therefore free to use this GIS as a basis for new, non-commercial, scholarly and creative works as long as each such GIS, website, and/or publication contains a statement that acknowledges Andrew Sluyter as this GIS's creator and CLIWOC as the source of the data.

My next post will be methodological: how I carried out the project, why I made choices I did, and so on. Other GIS postings will follow, each related to another aspect of the project.

View Larger Map

Purpose of this blog

I have created this blog to share the results of a project called an Internet-Based Geographic Information System (GIS) of Nineteenth-Century Atlantic Commodity Networks that I have been working on while a 2012-13 Digital Innovation Fellow of the American Council of Learned Societies.

Abstract. This project initiates an Internet-based GIS of nineteenth-century Atlantic commodity networks. Data come from logbooks of vessels and include daily position, cargo, and crew information. All data are in hand, derived from previous archival work and the public-domain CLIWOC database (Climatological Database for the World’s Oceans). In contrast to existing databases such as the Trans-Atlantic Slave Trade Database, which emphasize temporal analysis, the use of a GIS that associates every data point with a geographic location allows users to employ web browsers to spatially analyze and visualize the routes of voyages (rather than only embarkation and disembarkation ports); maritime literature related to routes; volumes of trade by route and season; and other information.

As various aspects of the project come to fruition over the next few months, I will post them here.

All materials that I post, including Web maps and applications, are © 2013 by Andrew Sluyter but open source and licensed through the Creative Commons as attribution-noncommercial 3.0, which allows others to use the data and programming to produce non-commercial derivative products.

For more information on me, my current position, other projects, courses, service, articles, and books please visit http://lsu.academia.edu/AndrewSluyter and http://en.wikipedia.org/wiki/Andrew_Sluyter.

OVERVIEW OF THE PROJECT

The interdisciplinary field of Atlantic Studies has delivered many new insights and matured to the point of self-reflection and -critique. Its scholarly monographs transcend regionalism to emphasize the interconnections among Europe, North America, Latin America, the Caribbean, and Africa; bring long-ignored actors to life; and conceptually transform the Atlantic into a dynamic space of flows rather than a dead space of separation. Its collaborative efforts have established Web-based databases such as the Trans-Atlantic Slave Trade Database (TSTD) that will stimulate new research for decades.

The goal of this project is to initiate another such Web-based database, stimulated by my research on the logbooks of the merchant vessels that participated in an Atlantic commodity network (Sluyter 2010). Unlike most other such efforts in the humanities, this database was developed as a Geographic Information System (GIS) and thereby is intrinsically spatial in order to engage “geographically integrated history” (Owens 2007). It focuses on mapping the routes of vessels between about 1750 and 1900 that carried cargos of coffee, sugar, spices, gold, and many other products as well as enslaved Africans between Europe, Africa, the Caribbean, South America, North America, and Asia.

Such analysis and visualization of Atlantic shipping networks has intellectual roots in the Annales School and present-day parallels in the Climatological Database for the World's Oceans, 1750-1850 (CLIWOC), a database that climatologists have constructed using the weather observations found in historic logbooks. A massive Annales project of the 1950s reconstructed Spanish shipping of the sixteenth- and seventeenth-century Atlantic to produce insights about the routes, timing, and other characteristics of the annual fleets that still inform our understanding of colonial Latin America. CLIWOC uses the Web to make public its database of daily vessel positions and weather observations from more than 3,000 Spanish, English, French, and Dutch logbooks dating to the 1700-1800s. Its purpose is to reconstruct historic climate for the era before establishment of widespread weather stations and climate satellites rather than analyze Atlantic shipping and commodity networks, but application of CLIWOC methods to the intellectual ambitions of the Annales School first suggested this project.

The inclusion of about 75 voyages drawn from CLIWOC and my own research on Catalan logbooks as well as nineteenth-century historic hurricane tracks from the National Oceanic and Atmospheric Administration demonstrates the potential for such a Web-based GIS approach to understanding the relationships among different commodity networks and social and environmental processes. It also facilitates enhancing the sophistication of related analyses and visualizations; serves the GIS on the Web to allow other scholars to use it to answer questions related to their own intellectual interests and to submit additional data for inclusion; maps the actual routes of some of the slave voyages included in TSTD rather than only the embarkation and disembarkation ports; and builds a teaching component into the project website that can stimulate and facilitate other humanities scholars to initiate more such Web-based GIS databases for a broader range of topics.

Such Web-based databases are inherently scalable. Scaling up would involve additional data contributed by users, as they have done for the TSTD. With the inclusion of additional voyages, users will be able to, for example, generate animated visualizations of the actual routes of specific vessels in relation to particular hurricane tracks; graph the relative volumes of trade along different routes in different seasons for a particular commodity; and link to other data, such as maritime art and literature associated with particular shipping lanes, or even particular vessels and voyages.

To facilitate scaling up, this blog includes extensive information on the data used and the methods to build the Web-based GIS.

Selected References

1. Bailyn, Bernard, Atlantic History: Concept and Contours (Cambridge, Massachusetts: Harvard University Press, 2005).
2. Boelhower, William, “I’ll Teach You How To Flow”: On Figuring Out Atlantic Studies, Atlantic Studies 1 (2001): 28-48.
3. Carney, Judith A., and Richard N. Rosomoff, In the Shadow of Slavery: Africa’s Botanical Legacy in the Atlantic World (Berkeley: University of California Press, 2009).
4. Elliott, John H., Empires of the Atlantic World: Britain and Spain in America 1492-1830 (New Haven: Yale University Press, 2006).
5. Eltis, David, The Rise of African Slavery in the Americas (Cambridge: Cambridge University Press, 2000)
6. Eltis, David and David Richardson, An Atlas of the Transatlantic Slave Trade (New Haven: Yale University Press, 2010).
7. Green, Jack and Philip Morgan, Atlantic History: A Critical Appraisal (Oxford: Oxford University Press, 2008).
8. Scott. Rebecca J., Public rights and private commerce: a nineteenth-century Atlantic creole itinerary, Current Anthropology 48 (2007): 237-256.
9. Sluyter, Andrew, The Hispanic Atlantic’s tasajo trail, Latin American Research Review 45 (2010): 98-120.
10. Sluyter, Andrew, Black Ranching Frontiers: African Cattle Herders in the Atlantic World, 1500-1900 (New Haven: Yale University Press, 2012).
11. Topik, Steven, Carlos Marichal, and Zephyr Frank, eds., From Silver to Cocaine: Latin American Commodity Chains and the Building of the World Economy, 1500-2000 (Durham, North Carolina: Duke University Press, 2006).