Despite its title, Map of a Nation is not a "biography of the Ordnance Survey". Rather, its sphere of interest is confined to British cartography 1747-1846. Moreover, despite its meticulous scholarship, the book is less a history than a celebration of the OS, an almost triumphalist account of an apparently irresistible ascent. While the account is sensitive to the military and governmental demands placed on the OS, the focus is on human endeavour and achievement, driven by the characters who ran the show: William Roy, who surveyed Scotland after the Jacobite Rebellion;William Mudge, who masterminded the survey of the British Isles; and Thomas Colby, the hyperactive perfectionist who succeeded him. Personality is the motivating force of history here.
This is ironic, as the maps these tireless cartographers laboured to produce have no one in them. Houses, yes; people, no. Like William Gilpin's advice to 18th-century painters aiming at picturesque effects, the landscape depicted has been drained of humanity. The British countryside, which even on today's maps dwarfs the straggling urban conurbations that punctuate it, is a depopulated spectacle.
Hewitt does not consider what is left out of OS mapping, nor what such absences expose. Yet there is much to be gained from reading between the contour lines. Poring over an OS map, there are plenty of names of cities, towns, villages, and hamlets, of parks, woods, and rivers. But fields are not named. Neither are the dedications of churches or chapels recorded.
At one level, the absence of fields' and saints' names is simply a practical necessity, but it does reveal the degree to which OS practice was – and still is – based on rationalist, Enlightenment thinking: a military and, emphatically, a metropolitan exercise. The OS map is effectively the view of the country from the city, in which the landscape is laid out for leisure activities, from walking tours in the 19th century to green-laning and geocacheing in the 21st.
In other words, land featured on these maps is not represented as a working agricultural environment. For centuries, field names were the co-ordinates of local rural culture, and parish saints did not simply identify a parish, but often provided a calendar for fairs and festivals. Yet all this was effaced from the country's perception of itself through OS cartography. In contrast, national history was writ large on the map.
Battlefields were recorded as part of the countryside, and ancient monuments were noted in references to tumuli, hut circles, or stone rows. This antiquarian emphasis is also a consequence of 18th-century preoccupations. Pre-Roman remains were believed to indicate that the British Isles shared an indigenous, non-classical history, and so these remains were a characteristic way in which 18th-century Britons could imagine that there was an underlying unity to the kingdom defined by the Acts of Union in 1707 and 1801.
This insufficiency of detail in the early OS maps, and their tendency to impose arithmetical order on the ineluctable environment, was questioned at the time by Romantic writers such as Coleridge and De Quincey. More recently, late-Romantic writers such as Iain Sinclair and his tribe have eloquently explored the "psycho-geography" of places, treating maps not as authoritative documents, but as abstract starting points for speculative encounters. In contrast, the cartographer and writer Tim Robinson has remapped the Aran Islands and Connemara in ways that rely not on the theodolite and heliostat – or on GPS technology, for that matter – but on the complex strata of memory and tradition that emerge from the experience of walking the ground.
In fact, it is the physical experience of walking that, ironically, demonstrates most compellingly the shortcomings of maps. Although Rachel Hewitt has followed in the footsteps of some of the cartographers she describes, her account is written almost entirely from the perspective of the library reading room. There are other perspectives that should remind us that, notwithstanding the extraordinary achievement of the Ordnance Survey and our everyday reliance on its work, the map is certainly not the territory.
Nick Groom's 'The Union Jack: a biography' is published by Atlantic