When Geology Encounters a Real Catastrophe
51
A New Way of Looking at Nature
The problem posed by earthquakes was not only theoretical but also
practical: the tremors of 1755-1756 necessitated new methods of investigation. In order properly to study the scale and distribution of this
phenomenon, a greatly increased number of observations were
needed, as it was no longer viable to limit data to a single account
specific to its locality. Each scientist had therefore to collate information by calling on his network of correspondents. In Paris this meant
putting together an overview drawn from various localities across the
country – Aix, Toulouse, Sedan, Beaune, and many more besides.
This empirical history in fact started in the 1740s when scientists first
encountered earthquakes in France. These low-to-moderate intensity
phenomena were more numerous than had previously been thought,
forcing scientists to construct new grids of reference and appropriate
procedures for observing them.
The protocol for observing earthquakes thus appeared in the
minutes of the Académie des sciences in the decade before the Lisbon
disaster. Responding to a request from René-Antoine Réaumur,
Chomel de Bressieu provided an account of the earthquake which hit
Annonay in 1740, giving the time of the shock, its duration in seconds, the area affected, the effects felt and further comments (for example, the differing sensations according to which floor of a building
one was on).
48 Similarly, in 1750, in the Académie de Toulouse the astronomer Antoine Darquier read letters sent to the Académie by a correspondent in Tarbes concerning the earthquakes which had recently
struck the Bigorre region.
49 With the increase in seismic research and
observations in 1755 and 1756, the criteria to be used were honed and
fixed. Scientific accounts came to resemble the letter written from
Geneva by Jean Jallabert in response to questions from Jean-Jacques
Dortous de Mairan about the earthquake of 9 December:
C’étoit 2 heures 23’ après midi. La plupart n’ont senti que deux secousses distantes
l’une de l’autre d’environ 30’’. Quelques personnes ont cru en avoir remarqué 3. Je
les jugeai sur la direction des oscillations de quelques corps suspendus du sud-est au
___________________________
48 Académie royale des Sciences, Registre des Procès-verbaux des séances, 23 mars
1740, vol. 59, fol. 58.
49 “Sur un tremblement de terre, & sur des effets singuliers de la foudre”, in Histoire
et Mémoires de l’Académie des sciences, inscriptions et belles-lettres de Toulouse
(Toulouse: 1784), II, pp. 15-19.
51
A New Way of Looking at Nature
The problem posed by earthquakes was not only theoretical but also
practical: the tremors of 1755-1756 necessitated new methods of investigation. In order properly to study the scale and distribution of this
phenomenon, a greatly increased number of observations were
needed, as it was no longer viable to limit data to a single account
specific to its locality. Each scientist had therefore to collate information by calling on his network of correspondents. In Paris this meant
putting together an overview drawn from various localities across the
country – Aix, Toulouse, Sedan, Beaune, and many more besides.
This empirical history in fact started in the 1740s when scientists first
encountered earthquakes in France. These low-to-moderate intensity
phenomena were more numerous than had previously been thought,
forcing scientists to construct new grids of reference and appropriate
procedures for observing them.
The protocol for observing earthquakes thus appeared in the
minutes of the Académie des sciences in the decade before the Lisbon
disaster. Responding to a request from René-Antoine Réaumur,
Chomel de Bressieu provided an account of the earthquake which hit
Annonay in 1740, giving the time of the shock, its duration in seconds, the area affected, the effects felt and further comments (for example, the differing sensations according to which floor of a building
one was on).
48 Similarly, in 1750, in the Académie de Toulouse the astronomer Antoine Darquier read letters sent to the Académie by a correspondent in Tarbes concerning the earthquakes which had recently
struck the Bigorre region.
49 With the increase in seismic research and
observations in 1755 and 1756, the criteria to be used were honed and
fixed. Scientific accounts came to resemble the letter written from
Geneva by Jean Jallabert in response to questions from Jean-Jacques
Dortous de Mairan about the earthquake of 9 December:
C’étoit 2 heures 23’ après midi. La plupart n’ont senti que deux secousses distantes
l’une de l’autre d’environ 30’’. Quelques personnes ont cru en avoir remarqué 3. Je
les jugeai sur la direction des oscillations de quelques corps suspendus du sud-est au
___________________________
48 Académie royale des Sciences, Registre des Procès-verbaux des séances, 23 mars
1740, vol. 59, fol. 58.
49 “Sur un tremblement de terre, & sur des effets singuliers de la foudre”, in Histoire
et Mémoires de l’Académie des sciences, inscriptions et belles-lettres de Toulouse
(Toulouse: 1784), II, pp. 15-19.