Map of a Nation (25 page)

Nevertheless, a series of close friendships was formed. In the years that
followed
the visit of Reynolds and Johnson to Devon, Zachariah and John Mudge were welcomed into their urban circle of friends. William Mudge’s grandfather subsequently visited London at least once a year until his death in 1769 and became a valued companion of Reynolds, Johnson, Garrick, Goldsmith and Burke. Zachariah was said to be ‘esteemed an idol’ by the men, a ‘learned and venerable old man’, and he was even considered by Reynolds to be ‘the wisest man he had ever met with in his life’. In the 1790s, after the outbreak of the French Revolution, Burke would arrange for Zachariah’s sermons to be republished in Britain to bolster the same royalist message as his own
Reflections on the Revolution in France
. William Mudge was still in the womb during Reynolds and Johnson’s Devon sojourn, but after
greeting the world for the first time on 1 December 1762 he grew up in
regular
contact with this illustrious circle of family friends. It is recorded that when Burke was introduced to one of Zachariah’s grandsons, perhaps William, he remarked happily: ‘I have lived in intimacy with two generations of Mudges, and have much pleasure in making the acquaintance of a third.’ Samuel Johnson became William’s godfather and when at the age of fifteen the young man was accepted into the Royal Military Academy in Woolwich, Johnson came to visit and bestowed upon him a guinea and a book. Although recognised as ‘a sharp boy’, Mudge was ‘not very attentive’ as a cadet. Nevertheless, his abilities were enough to gain a commission in the Royal Regiment of Artillery in 1779 and then to be sent to South Carolina to fight in the American War of Independence.

William Mudge returned to Britain from America in 1783 at the age of twenty-one. He had always been close to his older sister Jane, affectionately nicknamed ‘Jenny’, and in that same year she married Richard Rosdew, the heir to a prosperous estate called Beechwood, near Plympton, ‘one of the most comfortable and pleasant residences in the neighbourhood’. The Rosdews were already closely connected to the Mudges by a series of
marriages
, but Richard was a particularly impressive catch as a freeman of Plymouth, the town coroner and a good-humoured, gentle man to boot. In his new brother-in-law, William found a firm friend, and in the same year as Richard and Jenny’s wedding took place, his own life took an exciting turn. He was sent for training in the Drawing Room of the Tower of London, amongst the Board of Ordnance’s surveyors. Here William Mudge found himself falling in love with the daughter of one of his superiors, a
Major-General
Williamson of the Royal Artillery. We know little about Margaret Jane Williamson, but in the late 1780s she and William were married and in 1789 their eldest son Richard Zachariah Mudge was born.

At the Tower, William made up for his early neglect of his studies, and mathematics particularly began to entrance him. It was a preoccupation partially driven by rivalry. When his contemporary Henry Shrapnel was rumoured to have ‘made considerable progress in mathematics’, William Mudge refused to be outdone and applied to his old mathematics professor at the Royal Military Academy, Charles Hutton, for extra tuition. Shrapnel
went on to invent a particularly gruesome artillery shell. Mudge became ‘a first rate mathematician’ and in 1791 Hutton recommended him to Charles Lennox as an ideal candidate to help direct the Ordnance Survey.

21. William Mudge, by James Northcote, 1804.

 

It was partly thanks to his remarkable family that William Mudge’s
temperament
was well suited to this responsibility. From his father he had learned to take seriously the foibles and anxieties of others, and a later
biographer
described him as ‘a man of the nicest feelings of honor, [and] of the strictest integrity’. Mudge was cultured and eloquent and sensitive to civilian concerns as well as to military preoccupations. As we shall see, he was acutely aware of the power that maps wielded in the popular imagination. He came from a close-knit family and was said to be equally devoted to his own. But the task of directing a national map was hardly compatible with a full and rewarding personal life, and William Roy and David Watson had, as far as we know, both sacrificed the prospect of fulfilling relationships to the demands of the military. William Mudge’s passion for maps and his love for his wife and children would eventually pull him in conflicting directions.

 

T
HE
O
RDNANCE
S
URVEY
began straight away after Charles Lennox had appointed Edward Williams and William Mudge as its directors on 12 July 1791. The two men selected the same baseline that Roy had used seven years earlier during the Paris–Greenwich triangulation, the line that
traversed
5.19 miles of Hounslow Heath to the south-west of London. But in order that ‘this operation might not rest on
data
afforded by any former one’ and their calculations be as trustworthy as possible, Mudge and Williams insisted on remeasuring Roy’s base.

This decision appears to qualify William Roy’s earlier emphatic
statements
of the Paris–Greenwich triangulation’s superior exactitude. It certainly reveals the uncertain nature of accuracy in this period. It is accepted by historians of science that ‘accuracy’ was a relatively novel concern for eighteenth-century astronomers, geodesists and map-makers, who became preoccupied with the idea of the ‘quantifying spirit’ in attempting to emulate
the certainty of Newton’s
Principia Mathematicia
and realise the Enlightenment ideal of perfect measurement. The historian of science Thomas Kuhn has termed this quest for accuracy a ‘second scientific revolution’, after the first scientific revolution that is usually taken to refer to the publication of Copernicus’s
De revolutionibus orbium coelestium
(
On the Revolutions of the
Heavenly Spheres
) in 1543. But numerous factors could threaten the precision of a measurement, such as the minuscule erosion of instruments’ parts, often simply through use; the expansion and contraction of apparatus according to changes in temperature; imperfect eyesight; or mistakes in calculations. The eighteenth century witnessed strenuous attempts to counteract many of these distortions, including the development of unprecedentedly accurate instruments and the formulation of new mathematical methods designed to reconcile a number of conflicting measurements or observations into an accurate ‘mean’. But perfect accuracy could not be realised in an instant. As the century progressed, scientists and mathematicians moved slowly closer to the goal of precision by dealing with minor flaws and hindrances that had dogged earlier projects. Every failure of accuracy could help the next undertaking draw closer to the ideal. So when in 1790 the astronomer Francis Wollaston noticed that Roy’s measurements for the Paris–Greenwich
triangulation
were tarnished with a few errors, this set the scene for Mudge and Williams to redo that experiment and, in learning from Roy’s mistakes, to establish a measurement more accurate than any before.

On 23 July Mudge, Williams and Isaac Dalby, accompanied by eleven members of the Royal Artillery, travelled up the river Thames to Hounslow Heath. After initial checks and reconnaissances, on 15 August the re-
measurement
officially began. It took almost two and a half months to complete. As in Roy’s time, the events on the Heath were cause for excited festivities, especially on the first and last days of the base measurement. ‘While the sun shone out’ on 15 August, Joseph Banks, Nevil Maskelyne and several other members of the Royal Society clustered breathlessly around the measuring chains, which were used for the preliminary stages of the measurement. On 28 September, more celebrities gathered, including Charles Lennox, Jesse Ramsden and William Mudge’s old mathematics teacher, Charles Hutton, to witness the base measurement’s completion. Edward Williams was in his
element among these luminaries. After Banks sent the surveyors a ‘Keg of small Beer’ for sustenance, Williams purred his ‘Thanks, for the kind Attentions you shewed to us whilst on the Heath’. In some respects, these
festivities
marked ‘an official “handing over” ceremony’ from the Royal Society, which had overseen the Paris–Greenwich triangulation in the 1780s, to the Board of Ordnance, which was now responsible for the new national
triangulation
. But Banks would certainly not lose interest in the Trigonometrical Survey once the Royal Society was no longer responsible for its progress; nor would the Surveyors reject Banks’s future offers of assistance.

The Hounslow Heath baseline is, cartographically speaking, the most important spot in the British Isles. Until theodolites were replaced by
satellites
in the second half of the twentieth century, it was the bedrock of the national triangulation that underlay every single Ordnance Survey map. One cartographic historian has remarked that ‘seldom if ever had there been a line measured with so much care’. Williams, Mudge and Dalby were acutely aware of the significance of this piece of land. They noticed that the wooden pipes that had been ‘laid down by the General [Roy] for the
termination
of his Base’ at its two ends at Hampton Poor House and King’s Arbour in 1784 were now, seven years later, ‘in a very decayed state’. Keen that the baseline’s extent should be preserved ‘in a more permanent manner’, Charles Lennox arranged for Roy’s old wooden markers to be replaced by ‘heavy iron cannon’. Two decommissioned guns were shipped from Woolwich to the baseline’s southern and northern ends. Up-ending such heavy artillery into the precise spots was described as ‘an operation of a delicate nature, and attended with some difficulty’, but eventually the
cannons
were ‘fixed at the extremities of the base’. There they survive, remnants of cartographic history half-buried in two patches of ground whose
surroundings
have changed around them beyond all recognition.

 

T
HE BASELINE RE-MEASUREMENT
produced a result of 27,404.3155 feet, 0.3845 feet less than Roy’s original attempt. This discrepancy was caused
by ‘a small oversight’: his failure to compensate for temperature change. Once the remeasurement was completed, Williams and Mudge were faced with the daunting responsibility of planning the Ordnance Survey’s progress. Amid fears of a French invasion, a map of the south coast was a priority, so the two men decided to begin the national triangulation on the Sussex coastline and then progress to the counties that separated it from the prime target of London – namely, Surrey.

The Ordnance Survey was given a new, improved version of the
theodolite
that had accompanied Roy during the Paris–Greenwich triangulation. The original remained in the Royal Society’s possession. After that
instrument
’s
triumph, the East India Company had commissioned Jesse Ramsden to make an identical model for a survey of India. William Mudge described the ensuing creation as ‘of similar construction to that which was used by General Roy, but with some improvements’. Ramsden’s characteristic
perfectionism
had driven him to rebuild the entire instrument from scratch, tinkering and refining until every minor criticism, mostly concerning the theodolite’s microscopes, had been resolved. The result was a surveying instrument of unsurpassed accuracy. It also meant a bill presented to the East India Company wildly exceeding the original quote. They refused to pay and cancelled the order, and the instrument languished in Ramsden’s showroom until, in the excitement around the Ordnance Survey’s
foundation
, Charles Lennox caught wind of its existence and bought it for the new Trigonometrical Survey. Almost every member of the early Ordnance Survey reverently referred to the instrument as the ‘Great Theodolite’. Protective of his expensive new toy, Lennox urged Mudge ‘to avoid towers and high buildings’ when executing the triangulation: a near impossibility.