Mapping monuments. A landscape archaeology of the Ordnance Survey
Keith Lilley shares his recent research on the field practices of the early Ordnance Survey, and especially the monuments created 'in the field' by the OS as part of their mapping work 200 years ago
For those of us keen on exploring the great outdoors, one of the key pieces of kit is an Ordnance Survey (OS) map. Such a map invites discovery of landscapes, of plotting out routes and navigating terrain on the ground. Ordnance Survey maps open up the landscapes of Scotland. But what is rather less well-known is that these landscapes were shaped on the ground by those who mapped them. These legacies of our nation’s mapmakers can still be found across Scotland and await discovery.
200 years ago, the surveyors of the Ordnance Survey were busy in Scotland. One of the first steps in creating accurate national mapping was to establish a trigonometrical network.Triangulation provided map-makers with a series of important ground measurements from which to create scaled maps. In the early 1800s this task required laboriously covering the landscape with a network of trigonometrical stations and taking observations between these using a theodolite.
FIRST HAND ACCOUNTS
A glimpse of the extraordinary task that trigonometrical survey faced in Scotland is provided by first-hand accounts of those involved on the ground.The ardour and excitement offered by surveying in Scotland 200 years ago is revealed in letters and memoirs of the time, including those of Thomas Colby, then director general of the OS. One such account relates to summer 1819, when Colby and his team were in Glen Fiddich taking trigonometrical observations from the summit of nearby Corriehabbie Hill. Having camped overnight at a hunting lodge, the party of surveyors began ‘the really laborious part of the business… that of conveying the camp-equippage, instruments, and stores to the top of the mountain’.
On Corriehabbie itself they set up their camp, and here again this was no mean feat. Captain Colby, along with Major Dawson and Lieutenant Robe, ‘selected a spot of ground for the encampment’ close to the summit, and then found ‘a suitable place for a turf-hovel… in which to make a fire for cooking… and to serve a place of shelter and warmth for the men in tempestuous and severe weather’. The summit became the surveyors’ home from which to take their scientific observations, a site on which to set up ‘the great theodolite’. To take their theodolite observations on Corriehabbie, some of the men were first ‘employed in pulling down the conical pile of stones built around the stationstaff… setting up in its place the observatory-tent’.
What is remarkable about this account is not just what it reveals of the industry that lay behind the making of the nation’s maps, but the impacts their surveying had on the local landscape.
The creation of cairns, for marking the station sites, the construction of ancillary buildings and structures for cooking, for shelter, for observations, all left a mark on the ground.
BICENTENARY RESEARCH
With the bicentenary of this nationwide trigonometrical survey upon us, now is surely a good time to look more closely at these legacies of the early work of the Ordnance Survey in our local landscapes.
Some of these ‘Colby’s camps’, as the sites are known in Scotland, are fairly well-documented. A search for ‘Colby’ using canmore.org.uk, reveals a few examples where there are substantial physical remains to be seen. One of the most impressive is the now scheduled monument on the summit of Creach Bheinn (shown above), with its massive drystone windbreak wall that protects a group of hut circles that once afforded surveyors’ tents some shelter. However other such ‘sites of survey’ await recording and assessment, including the site of the camp on Corriehabbie where Colby and his men toiled.
A real opportunity exists to make use of the online web-mapping platforms available in Scotland, thanks to the National Library of Scotland and Historic Environment Scotland for example, with their aerial photographs and historic OS maps, and explore the upland landscapes of Scotland following in the surveyors’ footsteps.