Black Combe and the Ordnance Survey (Background: Whitcham)
Black Combe was important not just for the Ordnance Survey’s mapping of Cumbria – but for their mapping of the whole of Britain.
In the 17th century, the process known as Triangulation was invented (by a Dutchman, Willebrord Snell), which enormously improved the accuracy of surveying. The process involved a base-line, measured to a high degree of accuracy, from the two ends of which bearings were taken on a distant point using a theodolite or surveyor’s compass, and the distances to that point worked out by trigonometry. From that new point, plus one of the existing points on the base line, new sightings were made to another point – and so on, until the whole of the area to be mapped was covered with triangles.
By the mid-18th century, this system was being widely applied in Britain to mapping at county level: and a national triangulation was proposed in 1783 by General William Roy, who measured a base-line 5 miles long laid out on Hounslow Heath. This led, after Roy’s death in 1790, to the foundation of the Ordnance Survey; and the Principal Triangulation of Britain, which was carried out between 1791 and 1853, involving laying out more than 300 large triangles.
In 1808, William Mudge, Director of the Ordnance Survey arrived in Cumbria, and headed for Black Combe. Where Mudge got his intelligence about the site from is not known – but the extent of the prospects from Black Combe were well known, as was the fact that the fell had been used in Tudor times as a beacon. It was said that fourteen counties are visible from its summit (600m) on a clear day.
Settling in for the summer, Mudge and his team built themselves a dry-stone-walled hut, with fireplace and sleeping platforms (the remains of which are visible to this day) – and began work. From the summit, the team took bearings initially on four sites – Helvellyn, Coniston Old Man, the Calf of Man and Bleasdale Forest. They then went on to take many more secondary readings, including South Barrule (Isle of Man) to the west, Sca Fell (Lower Top) to the north, Ingleborough to the east and Bodafon (Anglesey) to the south.
With the initial triangles in place, the Ordnance Survey then began mapping the whole country from the south up: but having been diverted to Ireland for several years, they did not start the detailed (6 inch to the mile) mapping of Lancashire until 1841, and did not complete the county until 1855. Westmorland was surveyed between 1856 and 1860, and Cumberland was completed in 1865.
Wordsworth was fascinated by Mudge’s work, and visited him and his team on top of the fell He wrote two sonnets on the topic, which he went on to publish, in one of which (Written with a Slate Pencil, on a Stone, on the Side of the Mountain of Black Comb) he mentions that …
A geographic Labourer pitched his tent,
With books supplied and instruments of art,
To measure height and distance; lonely task,
Week after week pursued!
While in his poem View from the top of Black Comb he wrote of that view…
For from the summit of Black Comb (dread name
Derived from clouds and storms!) the amplest range
Of unobstructed prospect may be seen
That British ground commands:—low dusky tracts,
Where Trent is nursed, far southward! Cambrian hills
To the southwest, a multitudinous show;
And, in a line of eyesight linked with these,
The hoary peaks of Scotland that give birth
To Teviot's stream, to Annan, Tweed, and Clyde: —
Crowding the quarter whence the sun comes forth,
Gigantic mountains rough with crags; beneath,
Right at the imperial station's western base.
Main ocean, breaking audibly, and stretched
Far into silent regions blue and pale;—
And visibly engirding Mona's Isle,
Text by Bill Shannon
Photo of Black Combe from Walney Island, Bill Shannon
Norman Nicholson also wrote a poem about Black Combe. You can access it here https://allpoetry.com/from:-Black-Combe-White
And http://www.poetryatlas.com/poetry/poem/1536/view-from-the-top-of-black-comb.html
For a general history of the Ordnance Survey, see W A Seymour A History of the Ordnance Survey, (Dawson, 1980).
For a recent account of the work of the Ordnance Survey in Cumbria, see
Peter Wilson and Alan Smith ‘Bench marks and flush brackets in Keswick – a legacy of the Ordnance Survey’, Tr CWAAS, (2022) vol 22, pp.137-146.
For a map showing all the bearings taken from the site, see ‘Diagram shewing the Principal Triangulation for the Ordnance Survey of Great Britain and Ireland’ in William D. Shannon, Cumbria: 1000 years of maps, (Inspired by Lakeland, 2024), pp.204-5.
