Alain Corbin is a historian, specialist in the history of the senses, honorary professor at the University of Paris I Sorbonne. He answered questions from Sciences et Avenir.
Alain Corbin
This article is from the magazine Sciences et Avenir - Les Indispensables n°206, dated July/September 2021.
Sciences et Avenir:You make the Lisbon earthquake, which occurred on All Saints Day 1755, a key date in Earth sciences. Why?
Alain Corbin: It was a huge disaster - both earthquake and tidal wave, followed by a fire that lasted several days - in which at least 10,000 people perished. Now, instead of seeing in this misfortune the sole hand of God, scholars entered into explanation and analysis. After Voltaire and his Poem on the Lisbon Disaster , published in 1756, of Holbach then Diderot will put this kind of event not on the account of laws or divine punishments, but quite simply of natural causes. This is an essential turning point. It is also from 1755 that the Academy of Sciences, in France, leads a real policy of study of earthquakes. The scientific debate seeks to unlock this secret of nature. A space for discussion opens between scholars, who advance three types of explanation. The first invokes an underground fire. The second, which prevailed until the 20th century, a dilation of the air, producing sudden movements. The third considers the jerk as an instantaneous propagation of electric fluid in conductive bodies.
What was the state of knowledge at that time?
In the Age of Enlightenment, there were still many unknowns. In 1755, scholars described the sky in few terms:dark, bright, rainy, torrential, icy, or snowy. We know the trade winds, but we don't know anything about atmospheric circulation, the origin or the path of storms... It was not until the beginning of the 19th century that we began to understand that meteorological phenomena can have a very distant origin. . It was also in 1802 that the Briton Luke Howard presented his nomenclature of clouds and tried to explain their formation mechanisms and their evolution. Mists are then seen as terrestrial exhalations, and weather forecasting is the prerogative of the ancients, who know how to see and feel the sky.
This article is from the magazine Sciences et Avenir - Les Indispensables n°206, dated July/September 2021.
Sciences et Avenir:You make the Lisbon earthquake, which occurred on All Saints Day 1755, a key date in Earth sciences. Why?
Alain Corbin: It was a huge disaster - both earthquake and tidal wave, followed by a fire that lasted several days - in which at least 10,000 people perished. Now, instead of seeing in this misfortune the sole hand of God, scholars entered into explanation and analysis. After Voltaire and his Poem on the Lisbon Disaster , published in 1756, of Holbach then Diderot will put this kind of event not on the account of laws or divine punishments, but quite simply of natural causes. This is an essential turning point. It is also from 1755 that the Academy of Sciences, in France, leads a real policy of study of earthquakes. The scientific debate seeks to unlock this secret of nature. A space for discussion opens between scholars, who advance three types of explanation. The first invokes an underground fire. The second, which prevailed until the 20th century, a dilation of the air, producing sudden movements. The third considers the jerk as an instantaneous propagation of electric fluid in conductive bodies.
What was the state of knowledge at that time?
In the Age of Enlightenment, there were still many unknowns. In 1755, scholars described the sky in few terms:dark, bright, rainy, torrential, icy, or snowy. We know the trade winds, but we don't know anything about atmospheric circulation, the origin or the path of storms... It was not until the beginning of the 19th century that we began to understand that meteorological phenomena can have a very distant origin. . It was also in 1802 that the Briton Luke Howard presented his nomenclature of clouds and tried to explain their formation mechanisms and their evolution. Mists are then seen as terrestrial exhalations, and weather forecasting is the prerogative of the ancients, who know how to see and feel the sky.
The internal structure of the Earth is even less known, for lack of deep soundings. In the 18th century, two theories competed:the Plutonians, disciples of the Scottish geologist James Hutton, saw our planet as a ball of cooled fire, containing materials that were still very hot. The Neptunians, in the wake of the German Abraham GottlobWerner, believe that it was shaped by the seas.
Have we ever explored the poles and the depths of the oceans?
The poles will remain inaccessible until the 20th century! Some scholars, refusing the idea that the sea can freeze, think that they shelter a free sea, past the obstacle of ice coming from the continents. Many expeditions fail, crews perish because of the cold or the wind... James Cook, who realizes the first circumnavigation of Antarctica (1772-1775), stumbles on the ice floe and concludes that there is no continent at the pole South. The abyss also remains a mystery. Man only knows the shallow depths reached in apnea by sponge fishermen. And scientists are reluctant to the idea of deep seas.
Have religions been an obstacle to knowledge of the Earth?
Geological history has long been obliterated by biblical history. For Christianity - in other words Europe and the colonial empires - it is the Bible that prevails:the Earth and all the celestial bodies were created by God. In the 17th century, Bossuet, an eminent personality, estimated the age of the planet at around 6,000 years. The episode of the Flood recounted in Genesis, which it justifies by the wickedness of men, persists even in the scientific explanations of the century through diluvialist theories:it is the waters of the Great Abyss that would have shaped the Earth. The imagination takes over inaccessible places, with great emotional power. We see the abyss as a hidden part of Creation, if not as the dark side of the world. The volcano seems to be in direct contact with the bowels of the Earth, which the historian Michelet, in the 19th century, saw as a beating heart. The poles are home to a monstrous bestiary populated by dragons or unicorns. Heaven, on the other hand, belongs to the kingdom of God.
According to you, the 1860s saw the acceleration of scientific knowledge of the Earth. Why?
We are then witnessing a conjunction of phenomena which makes possible an unprecedented progress in knowledge. We first observe the decline of references to the Bible, concomitant with the rise of a scientific and rational spirit resulting from the Enlightenment. There is also the commitment of States to support scientific work. In meteorology, for example, the Paris Observatory piloted, from June 1856, a national meteorological telegraph network, under the leadership of Napoleon III. But above all, these developments are made possible by spectacular technical progress:in meteorology, readings and the global exchange of data make it possible to map the sky and monitor air masses. In the 1860s, the balloon became dirigible and instrumented. Aerial observations helped to shape the atmospheric space, until the meteorologist Léon Teisserenc de Bort presented his work in 1902, distinguishing between the lower and upper atmospheres, troposphere and stratosphere. Knowledge of volcanoes is also progressing.
In 1866, after a long study of Santorini and the Cyclades, Ferdinand Fouqué described the formation of the volcanic cone by the accumulation of rejected materials. The volcanologist will advance the promising theory of lines of fragility in the earth's crust. Ignorance of glaciers had already declined between 1820 and 1840, with the hypothesis of an ice age presented in 1837 by the Swiss Louis Agassiz. This knowledge, supported by geological observation, finally explains the landscapes, with the presence of erratic blocks even in the valleys.
This progress in knowledge is parallel to the development of new means of communication and the acceleration of exchanges?
Exactly. On the one hand, the proliferation of learned societies stimulates research and interest in science, as does the organization of international congresses in all disciplines. On the other hand, the electrification and proliferation of telegraph cables - which go hand in hand with a better knowledge of the seabed - also contribute to the acceleration of knowledge thanks to the rapid exchange of information on the scale of the world. For the record, the first transatlantic communication took place in 1858. Until then, the distant causes were unknown.
An example:at the end of 1815, the Indonesian volcano Tambora erupts, which will generate in the northern hemisphere, for nearly two years, climatic cooling, dry fogs, torrential rains, veiled sun. .. Disturbance that we will only associate a century later with the eruption. In 1883, less than seventy years after Tambora, another Indonesian volcano exploded, Krakatoa. The cables and the global network of measuring instruments then make it possible to follow almost instantly the chronology of the eruption, its impact on the atmospheric composition, the height of the tidal waves... One proof among many others of the spectacular leap performed by Earth Sciences at that time.
Comments collected by François Folliet