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    Chalice at WhereCamp

    November 23rd, 2010

    I was lucky enough to get to WhereCamp UK last Friday/Saturday, mainly because Jo couldn’t make it. I’ve never been to one of these unconferences before but was impressed by the friendly, anything-goes atmosphere, and emboldened to give an impromtu talk about CHALICE. I explained the project setup, its goals and some of the issues encountered, at least as I see them –

    • the URI minting question
    • the appropriateness (or lack of it) of only having points to represent regions instead of polygons
    • the scope for extending the nascent historical gazetteer we’re building and connecting it to others
    • how the results might be useful for future projects.

    I was particularly looking for feedback on the last two points: ideas on how best to grow the historical gazetteer and who has good data or sources that should be included if and when we get funding for a wider project to carry on from CHALICE’s beginnings; and secondly, ideas about good use cases to show why it’s a good idea to do that.

    We had a good discussion, with a supportive and interested audience. I didn’t manage to make very good notes, alas. Here’s a flavour of the discussion areas:

    • dealing with variant spellings in old texts – someone pointed out that the sound of a name tends to be preserved even though the spelling evolves, and maybe that can be exploited;
    • using crowd-sourcing to correct errors from the automatic processes, plus to gather further info on variant names;
    • copyright and IPR, and the fact that being out of print copyright doesn’t mean there won’t be issue around digital copyright in the scanned page images;
    • whether or not it would be possible – in a later project – to do useful things with the field names from EPNS;
    • the idea of parsing out the etymological references from EPNS, to build a database of derivations and sources;
    • using the gazetteer to link back to the scanned EPNS pages, to assist an online search application.

    Plenty of use cases were suggested, and here are some that I remember, plus ideas about related projects that it might be good to tie up with:

    • a good gazetteer would aid research into the location of places that no longer exist, eg from Domesday period – if you can locate historical placenames mentioned in the same text you can start narrowing down the likely area for the mystery places;
    • the library world is likely to be very interested in good historical gazetteers, a case mentioned being the Alexandria Library project sponsored by the Library of Congress amongst others;
    • there are overlaps and ideas to share with similar historical placename projects like Pleiades, Hestia and GAP (Google Ancient Places).

    I mentioned that, being based in Edinburgh, we’re particularly keen to include Scottish historical placenames. There are quite a few sources and people who have been working for ages in this area – that’s probably one of the next things to take forward, to see if we can tie up with some of the existing experts for mutual benefit.

    There were loads of other interesting presentations and talk at WhereCamp… but this post is already too long.

    Linking historic places: looking at Victoria County History

    November 19th, 2010

    Stuart Dunn mentioned the Victoria County History in his writeup of discussions with the Clergy of the Church of England Database project. Both resources are rich in place-name mentions and historic depth; as part of the Chalice project we’re investigating ways to make such resources more searchable by extracting historic place-names and linking them to our gazetteer.

    Here’s a summary of some email conversation between Stuart, Claire Grover, Ross Drew at EDINA and myself while looking at some sample data from VCH.

    The idea is to explore the possibilities in how Chalice data could enhance / complement semi-structured information like VCH (or more structured database-like sources such as CCED).

    It would be very valuable, I think, to do an analysis of how much effort and preparation of the (target) data is needed to link CHALICE to VCH, and a more structured dataset like CCED. By providing georeferences and toponym links, we’re bringing all that EPNS documentary evidence to VCH, thus enriching it.

    It would be very interesting if we were able to show how text-mining techniques could be used to add to the work of EPNS (extracting place references that aren’t listed, and suggesting them to editors along with suggested attestations (source and date).

    In the more immediate future; this is about adding links to Chalice place-references to other resources, that would allow us to cross-reference them and search them in interesting ways.

    Text mining isn’t absolutely necessary to map the EPNS place names to the VCH text. On the other hand, LTG have all the processing infrastructure to convert formats, tokenise the text etc. so we could put something in place very quickly. It wouldn’t be perfect but it would demonstrate the point. I’ve not seen the CCED data, so don’t know how complex that would be.

    Here’s a sample reference to a volume of VCH that may have some overlap with the Shropshire content we have in “born-digital” form from EPNS. There’s the intriguing prospect of adding historic place-name text mining/search in at the digitisation phase, so resources can be linked to other references as soon as they’re published.

    Structuring a Linked Data namespace for places

    November 10th, 2010

    Thoughts on structuring a namespace for historic English places, for our prototype Linked Data version of the English Place Name Survey; how do others do it? Our options seem to be:

    1. give each placename a numeric identifier that can be part of the link
    2. create a more human-readable identifier based on the name, to use as part of the link.

    Numeric identifiers for places look like common practise. uses numbers to create links for places – so “is”, or refers to, Baschurch in Shropshire. Though the coordinates of the point may change, the number is associated with the name, and it remains the same.

    Ordnance Survey Linked Data also uses a numeric ID to create its link that stands for (the same) Baschurch –

    The Linked Data Patterns online book has a set of patterns for identifying URIs. The patterns are focused on use with systems that are already database-based, with some design thought having gone into how IDs look, how they can be looked up, and how their persistence is guaranteed.

    The point here is that the numeric identifiers still need careful curation – an organisational guarantee that the identifiers will stay the same for the predicatable future.

    We’re using a relational database (PostGIS) rather than a triplestore, to hold the Chalice data (because the data model won’t really change or expand). We can’t just use IDs that are created automatically by the database when items are inserted into it, because those might change if the names are inserted in a different order.

    During Chalice we’re not building a be-all-end-all system, but rather prototyping an approach to text mining and georeferencing places can be used to turn an amazing hand-created resource into a 21st century Linked Data gazetteer; leaving behind open source tools to make sure the process can be repeated again with more digitised text.

    But we’re not building something to throw away; we want to make sure the links we create can be preserved – that they won’t be broken and won’t change their meanings. So it may be better for us to structure our namespace using the EPNS names themselves, and the order in which they occur in the printed volumes of EPNS.

    The EPNS volumes are arranged county-by-county – each county has its own editor, and so may have different layout, style guidelines, level of detail for things like field-names, and the presence or absence of OS Grid coordinates, more or less according to the whims of the county editor. (We’ve focused on Cheshire, but LTG have been developing test parsers for samples of several different counties.)

    So it makes sense to include the county name in our namespace. This also helps with disambiguation – which Walton is this Walton? But there will still be cases where several places, in quite different locations, but still within the same county, share a name. In this case, we’d also give the places a numeric identifier (Walton-1, Walton-2) in the order in which they appear in the EPNS text.

    Some volumes of EPNS give us OS National Grid coordinates for the “major names”, others don’t. Where the “major name” exists in one or more gazetteers (geonames, OS Open Data), the LTG’s georesolver tool can create some of the missing links using the Unlock Places gazetteer cross-search.

    More potentially useful context in the work of the UK Location Programme on Linked Data namespaces for places – a recent Guide to Linked Data and the UK Location Strategy, and last year’s guidance on Designing URI sets for Location.

    One more potential complication, which is a fairly subtle issue of semantics – does a link identify a place, or a description of a place? Ordnance Survey Research try to make the difference clear by using a different namespace for ‘IDs for places’ and ‘IDs for documents describing places’.
    So “is” Baschurch; and “is” the description of Baschurch. To make sure we’re properly confused, when a human looks up the /id/ link using a web browser, the browser is redirected to the human-readable /doc/. To actually get hold of the Linked Data description of Baschurch (including the coordinates for it in the 50K gazetteer), one has to specifically request the machine-readable, rather than human-readable, version of the link, like this:

    curl -L -H "Accept: application/rdf+xml" :) - but now you know that!

    This took me a little while, and some back-and-forth with John Goodwin from OS Research on “Twitter”, to figure out, which is why I thought it worth writing down here.

    Discussions with CCED (or how I learned to stop worrying about vagueness and love point data)

    November 8th, 2010

    I met recently with Prof. Stephen Taylor of the University of Reading. Prof. Taylor is one of the investigators of the Clergy of the Church of England (CCED) database project; whose backend development is the responsibility of the Centre for Computing in the Humanities (CCH). Like so many other online historical resources, CCED’s main motivation is to bring things together, in this case information about the CofE clergy between 1540 and 1835, just after which predecessors to the Crockford directory began to appear. There is, however, a certain divergance between what CCED does and what Crockford (simply a list of names of all clergy) does.

    CCED started as a list of names, with the relatively straightforward ambition of documenting the name of every ordained  person between those dates, drawing on a wide variety of historical sources. Two things fairly swiftly became apparent: that a digital approach was needed to cope with the sheer amounts of information involved (CD-ROMS  were mooted at first), and that a facility to build queries around location would be critical to the use historians make of the resource. There is therefore clearly scope for considering how Chalice and CCED might complement one another.

    Even more importantly however, some of the issues which CCED have come up against in terms of structure have a direct bearing on Chalice’s ambitions.  What was most interesting from Chalice’s point of view was the great complexity which the geographic component contains. It is important to note that there was no definitive list of English ecclesiastical parish names prior to the CCED (crucially, what was needed, was a list which also followed through the history of parishes – e.g. dates of creation, dissolution, merging, etc.), and this is a key thing that CCED provides, and is and of itself of great benefit to the wider community.

    Location in CCED is dealt with in two ways: jurisdictional and geographical (see this article). Contrary to popular opinion, which tends to perceive a neat cursus honorum descending from bishop to archdeacon to deacon to incumbent to curate etc, ecclesiastical hierarchies can be very complex. For example, a vicar might be geographically located within a diocese, and yet not report to the bishop responsible for that diocese (‘peculiar’ jurisdictions).

    In the geographic sense, location is dealt with in two distinct ways – according to civil geographical areas, such as counties, and according to what might be described as a ‘popular understanding’ of religious geography, treating a diocese as a single geographic unit. Where known, each parish name has a date associated with it, and for the most part this remains constant throughout the period, although where a name has changed there are multiple records (a similar principle to the attestation value of Chalice names, but a rather different approach in terms of structure).

    Sub-parish units are a major issue for CCED, and there are interesting comparisons in the issues this throws up for EPNS. Chapelries are a key example: these existed for sure, and are contained with CCED, but it is not always possible to assign them to a geographical footprint (I left my meeting with Prof. Taylor considerably less secure in my convictions about spatial footprints) at least beyond the fact that, almost by definition, they will be been associated with a building. Even then there are problems, however. One example comes from East Greenwich, where there is a record of a curate being appointed, but there is no record of where the chapel is or was, and no visible trace of it today.

    Boundaries are particularly problematic. The phenomenon of ‘beating the bounds’ around parishes only occurred where there was an economic or social interest in doing this, e.g. when there was an issue of which jurisdiction tithes should be paid to.  Other factors in determining these boundaries was folk memories, and the memories of the oldest people in the settlement. However, it is the case that, for a significant minority of parishes at least, pre Ordnance Survey there was very little formal/mapped conception of parish boundaries.

    For this reason, many researchers consider that mapping based on points is more useful that boundaries. An exception is where boundaries followed natural features such as rivers. This is an important issue for Chalice to consider in its discussion about capturing and marking up natural features: where and how have these featured in the assignation and georeferencing of placenames, and when?

    A similar issue is the development of urban centres in the late 18th and 19th centuries: in most cases these underwent rapid changes; and a system of ‘implied boundaries’ reflects the situation then more accurately than hard and fast geolocations.

    Despite this, CCED reflects the formal structured entities of the parish lists. Its search facilities are excellent if you wish to search for information about specific parishes whose name(s) you know, but, for example, it would be very difficult to search for ‘parishes in the Thames Valley’; or (another example given in the meeting), to define all parishes within one day’s horse riding distance of Jane Austen’s home, thus allowing the user to explore the clerical circles she would have come into contact with but without knowing the names of the parishes involved.

    At sub-parish level, even the structured information is lacking. For example, there remains no definitive list of chapelries.  CCED has ‘created’ chapelries, where the records indicate that one is apparent (the East Greenwich example above is an instance of this). In such cases, a link with Chalice and/or Victoria County History (VCH) could help establish/verify such conjectured associations (posts on Chalice’s discussions with VCH will follow at some point).

    When one dips below even the imperfect georeferencing of parishes, there are non-geographic, or semi-geographic, exceptions which need to be dealt with: chaplains of naval vessels are one example; as are cathedrals, which sit outside the system, and indeed maintain heir own systems and hierarchies. In such cases, it is better to pinpoint the things that can be pinpointed, and leave it to the researcher to build their own interpretations around the resulting layers of fuzziness. One simple point layer that could be added to Chalice, for example, is data from Ordnance Survey’s describing the locations churches: a set of simple points which would associate the names of a parish with a particular location, not worrying too much about the amorphous parish boundaries, and yet eminently connectible to the structure of a resource such as CCED.

    In the main, the interests that  CCED share with Chalice are ones of structural association with geography. Currently, Chalice relies on point based grid georeferencing, where that has been provided by county editors for the English Place Name Survey. However, the story is clearly far more complex than this.   If placename history is also landscape history, one must also accept that it is also intimately linked to Church history; since the Church exerted so much influence of all areas of life of so much of the period of history in question.

    Therefore Chalice should consider two things:

    1. what visual interface/structure would work best to display complex layers of information
    2. how can the existing (limited) georeferencing of EPNS be enhanced by linking to it?

    The association of (EPNS, placename, church, CCED, VCH) could allow historians to construct the kind of queries they have not been able to construct before.

    Linked Data choices for historic places

    November 5th, 2010

    We’ve had some fitful conversation about modelling historic place-names extracted from the English Place Name Survey as Linked Data, on the Chalice mailing list.
    It would be great to get more feedback from others where we have common ground. Here’s a quick summary of the main issues we face and our key points of reference, to start discussion, and we can go into more detail on specific points as we work more with the EPNS data.

    Re-use, reduce, recycle?

    We should be making direct re-use of others’ vocabularies where we can. In some areas this is easy. For example, to represent the containment relations between places (a township contains a parish, a parish contains a sub-parish) we can re-use the some of the Ordnance Survey Research work on linked data ontologies – specifically their vocabulary to describe “Mereological Relations” – where “mereological” is a fancy word for “containment relationships”.

    Adapting other schemas into a Linked Data model

    One project which provides a great example of a more link-oriented, less geometry-oriented approach to describing ancient places is the Pleaides collection of geographic information about the Classical ancient world. Over the years, Pleaides has developed with scholars an interesting set of vocabularies, which don’t take a Linked Data approach but could be easily adapted to do so. They encounter issues to do with vagueness and uncertainty that geographical information systems concerning the contemporary world, can overlook. For example, the Pleiades attestation/confidence vocabulary expresses the certainty of scholars about the conclusions they are drawing from evidence.

    So an approach we can take is to build on work done in research partnerships by others, and try to build mind-share about Linked Data representations of existing work. Pleiades also use URIs for places…

    Use URIs as names for things

    One interesting feature of the English Place Name Survey is the index of sources for each set of volumes. Each different source which documents names (old archives, previous scholarship, historic maps) has an abbreviation, and every time a historic place-name is mentioned, it’s linked to one of the sources.

    As well as creating a namespace for historic place-names, we’ll create one for the sources (centred on the five volumes covering Cheshire, which is where the bulk of work on text correction and data extraction has been done. Generally, if anything has a name, we should be looking to give it a URI.

    Date ranges

    Is there a rough consensus (based on volume of data published, or number of different data sources using the same namespace) on what namespace to use to describe dates and date ranges as Linked Data? At one point there were several different versions of iCal, hCal, xCal vocabularies all describing more or less the same thing.

    We’ve also considered other ways to describe date ranges – talking to Pleiades about mereological relations between dates – and investigating the work of Common Eras on user-contributed tags representing date ranges. It would be hugely valuable to learn about, and converge on, others’ approaches here.

    How same is the same?

    We propose to mint a namespace for historic place-names documented by the English Place Name Survey. Each distinct place-name gets its own URI.

    For some of the “major names”, we’ve been able to use the Language Technology Group’s georesolution tool to make a link between the place-name and the corresponding entry in

    Some names can’t be found in geonames, but can be found, via Unlock Places gazetteer search, in some of the Ordnance Survey open data sources. Next week we’ll be looking at using Unlock to make explicit links to the Ordnance Survey Linked Data vocabularies. One interesting side-effect of this is that, via Chalice, we’ll create links between geonames and the OS Linked Data, that weren’t there before.

    Kate Byrne raised an interesting question on the Chalice mailing list – is the ‘sameAs’ link redundant? For example, if we are confident that Bosley in is the same as Bosley in the Cheshire volumes of English Place Name Survey, should we re-use the geonames URI rather than making a ‘sameAs’ link between the two?

    How same, in this case, is the same? We may have two, or more, different sets coordinates which approximately represent the location of Bosley. Is it “correct”, in Linked Data terms, to state that all three are “the same” when the locations are subtly different?
    This is before we even get into the conceptual issues around whether a set of coordinates really has meaning as “the location” of a place. Geonames, in this sense, is a place to start working out towards more expressive descriptions of where a place is, rather than a conclusion.

    Long-term preservation

    Finally, we want to make sure that any URIs we mint are going to be preserved on a really long time horizon. I discussed this briefly on the Unlock blog last year. University libraries, or cultural heritage memory institutions, may be able to delegate a sub-domain that we can agree to long-term persistence of – but the details of the agreement, and periodic renewal of it due to infrastructural, organisational and technological change, is a much bigger issue than i think we recognise.