History of Surveying II

 

from the Renaissance to modern day

Double levels of the type used by the Abbé Picard at the end of the 17th
Double levels of the type used by the Abbé Picard at the end of the 17th
(© Rights reserved)

From the time of the Renaissance, many inventions emerged due to public demand. Then in the 19th century cartography made giant strides before a new wave of innovations revolutionised 20th century instrumentation...

 

Gallileo did not actually invent the telescope. However, he improved it so much that he is often attributed with having invented it. With the appearance of the first Dutch glasses in 1608, which magnified three times, the Italian scientist succeeded in perfecting a lens which magnified six and then ten times. In turning this towards the sky (1609-1610), he opened the door to modern astronomy, discovering the craters on the moon, the stars in the Milky Way, sunspots and Jupiter’s satellites.

More symbolically, the arrival of the telescope marked a stage where Man was taking measurements of the world, in parallel with the discoveries of the Renaissance. Mankind’s view was transformed and this was the start of a long transformation which would lead to modern-day surveying.

However, inventions are worth nothing in themselves without a general recognition of the practical usage, eg the great works initiated by Louis XIV paved the way for these new discoveries to be employed. At the same time, the introduction of firearms made it necessary to revise military strategy which meant that detailed maps of France were required. All of this encouraged the progression of surveying.

Further innovations followed with the invention of the bubble level in 1666 and then the optic level, invented by the Abbé Jean Picard. Twenty years later, the Dutchman Christian Huygens improved the process, increasing the range to more than 100 metres. It was also the Abbé Picard who Colbert (the General Controller of Finances appointed by Louis XIV in 1665) put in charge of producing maps of France <>.

Further innovations

The 18th century started with the publication, in 1702, of the first complete treatise on surveying under the title <> (Practical Surveying). The foundations for modern geodesics were established in the same period. Pascal and Huygens used triangulation to demonstrate the flattening of the Earth at the Poles. However, the theory would not be completely validated until after the Condamien and Maupertuis expeditions to the Pole and the Equator in 1735-1737.

These explorations opened up new horizons in cartography as well as surveying. It required two generations of the Cassini family to achieve the first general map of the kingdom of France. It was initiated by the father, César-François in 1754 and was eventually completed by his son, Jean-Dominique, in 1815! During this time further new mapping was ordered by Napoleon and the resultant and now famous map of France to the scale of 1/80 000 was finally completed in 1880. The Emperor also ordered a cadastral survey which came into use in 1807.

In 1799, the metre, newly adopted by the Science Academy, was defined as the quarter of ten parts per million of the arc of meridian. Almost a century would pass before countries of the world would attempt to coordinate their geodesic systems data at the first congress of the International Geodesic Association (1886). During this time (1897) level zero in France was set at the Marseilles tide gauge.

Throughout, the transformation of instrumentation continued. Use of the theodolite, invented in the 18th century, expanded during the intervening century. From the 1950s, it was then the theodolite and subsequently the tacheometer which came into wider usage. This transformation has continued until today when the power of calculation using computer science and information transmitted in real time via satellite, as well as other Earth sciences, has revolutionised the world of surveying in the era of geomatics…

We are greatly indebted to the Association pour la Mémoire du Patrimoine de
l’Equipement (Association for Remembrance of Heritage Equipment), for the supply of the following illustrations from their section <>, as well as a great deal of information on the history of surveying.

A 1960s model of a Sanguet tacheometer with variable tilt
A 1960s model of a Sanguet tacheometer with variable tilt
(© Lycée Dorian)