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March 2014
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
of compiling an atlas embracing the whole of India. On the
initiative of John Tringle, who surveyed routes with great en-
thusiasm, a military ‘Corps of Guides’ was established. This
Corps also contributed largely to the surveys of the Madras
Presidency for the next 30 years. It was in 1787 that Michael
Topping, a marine officer, broke away from the eternal meth-
od of Perambulator Traverse and ran a 300-mile line of tri-
angles along the coast from Madras to Palk Strait. It was he
who built a permanent astronomical observatory in Madras
in 1793 and founded the first surveying school in 1794. In
1796 and 1810, the Presidencies of Bombay and Madras got
their own Surveyors General with the appointment of Lt Gen.
Charles Reynolds and Col. Colin Mackenzie as the respective
Surveyors General. It was on the
first of May 1815 that the Directors,
finding it wasteful to maintain three
separate and independent Survey-
ors General, appointed Mackenzie
as the Surveyor General of India.
The credit of the first surveys of the
Brahmaputra in Assam in 1794, and
that of the Irrawady river in Burma
go to Thomas Wood. The mission
also collected interesting informa-
tion about people, tribes and general
geography of Assam and Burma,
about which nothing whatever had
been known before. India was one of
the earliest countries to establish a
regular government survey organi-
zation and to commence systematic
surveys — a few years before even
the Ordnance Survey of UK.
“It was very fortunate that a
man of the genius and resolution of
Lambton was in the subcontinent
to lay the foundation of the ‘Great Trignometrical Survey of
India’ a few years before similar projects were undertaken
by France and England. In November 1799, he put forward
his proposal for a Mathematical and Geographical Survey
that should extend right across the Peninsula from sea to
sea, controlled by astronomical observations carried out on
scientific principles, capable of extension in any direction and
to any distance. He started his work from Madras where, in
early 1802, he measured the famous base line at Saint Thom-
as’ Mount as a start for his triangulation, north and south
through Carnatic India and across the Peninsula, with his
famous 36-inch great theodolite. He completed a meridional
arc from Cuddalore to Madras observing latitude at both ends
and obtaining a value for the length of a degree that was es-
sential for his scientific work. By 1815, he had nearly covered
the whole Peninsula south of the river
Kistna
(Krishna) with
a network of triangulations braced by main cross belts. To
him goes the distinction of measuring the longest geodetic arc
closest to the equator, from Cape Comorin to the 18° parallel.
“In 1806, a subaltern came to India at the tender age of six-
teen. He was none other than Lieutenant George Everest. He
joined Lambton in 1818. Lambton died at work on 20 January
1823 at Hinganghat at the age of 70. General Walker recogniz-
ing his work wrote in 1870, ‘of all Col. Lambton’s contributions
to geodesy, the most important are his measurements of me-
ridional arcs, the results of which have been employed up to
the present time in combination with those of other parts of the
globe, in all investigations of the figure of the earth.’ Lambton’s
mantle fell on the worthy shoulders of George Everest. Everest
felt the need for basing the surveys on a rigid reference frame-
work. This raised the problem of finding a suitable reference
spheroid to fit the shape of the earth’s gravity equi-potential
surface for India and the adjacent
countries. Everest realized that the
Indian subcontinent was too large
for basing surveys on an osculating
sphere, let alone a tangent or secant
plane. Everest therefore, started his
control work from Kalianpur in Mad-
hya Pradesh, more or less in the centre
of India. Here he made astronomical
observations and treated the astro-
nomical latitude, longitude and the
plumbline at that place as error-free.
With Kalianpur as the center, he con-
ceived covering the length and breadth
of India by a gridiron of triangular
chains, as opposed to the network of
triangles conceived by Lambton. He
brought to surveying greater accuracy
and rigorous observational procedures
besides devising and refining the
instruments. He introduced the obser-
vation of astronomical azimuths from
pairs of circumpolar stars, ray traces
for long lines,
etc
. His redesigned 36-inch great theodolite is fa-
mous today. He replaced the chain with Colby’s base-line appa-
ratus and 10-foot compensation bars, with which he measured
various bases. He completed the great meridional arc from
Cape Comorin to Banog in the first Himalaya near Mussoorie,
a length of 2400 km. Everest made the government agree to
the revision of Lambton’s work, based on more accurate instru-
ments and the procedures as laid down by him. Later, in 1830,
he was appointed as the Surveyor General of India but, much
against the wishes of the then government, he continued to
devote much time to the Great Meridional Arc. This was com-
pleted by him in 1841 and he utilized the last 2 years of his ser-
vice in its computations and adjustments. The work and norms
laid down by Everest have stood the test of time. The Everest
spheroid, evolved by him in the year 1830, is not only still being
used by India but also by Pakistan, Nepal, Burma, Sri Lanka,
Bangladesh, Bhutan and other south-east Asian countries.
“We can only grasp the significance of his monumental
work if we can visualize India of the early nineteenth century
THE USE OF LAPLACE STATIONS
HAD NOT YET BEEN ADOPTED
BY THE SURVEY OF INDIA;
CONSEQUENTLY ERRORS IN
AZIMUTH AND POSITION WERE
INTRODUCED. THESE ERRORS
ARE PARTICULARLY EVIDENT IN
THE TRIANGULATION SERIES
OF SOUTHERN INDIA. THE 1880
ADJUSTMENT HAS HOWEVER,
REMAINED THE BASIS OF ALL
INDIAN TRIANGULATION AND
MAPPING. THEREFORE THERE IS
NO SUCH THING AS AN “INDIAN
DATUM;” IT IS ONLY AN ADJUST-
MENT! (JMN, 21 JUNE 1997)
