Progrès et harmonie : La Grande Période de Jean Delormel

Dans La Grande Période, publiée en 1790, 1796 et 1805, Jean Delormel défend l’idée que l’inclinaison de l’axe de rotation de la Terre diminue lentement et que par conséquent l’humanité avance très lentement vers un nouvel âge d’or. Sa théorie présente trois paradoxes : d’une part, le temps est à la fois progressif et cyclique ; d’autre part, le progrès est à la fois très lent et très rapide ; enfin, le progrès est fait d’événements heureux et malheureux et, par conséquent, la Révolution française peut être l’un ou l’autre, selon le contexte de publication. Delormel défend l’utilité sociale d’une théorie de l’harmonie qui doit susciter l’espoir et qui peut avoir des applications concrètes. Bien qu’elle soit fondée sur l’astronomie et qu’elle s’appuie sur des éléments de la tradition biblique, sa science est une science pratique qui procède par deux opérations principales : simplifier et concilier. Le théoricien de l’harmonie se présente ainsi comme celui qui dépasse les querelles et qui fournit les moyens de les éteindre. Écrivant pour la concorde et pour le progrès, il peut offrir ses services aux institutions nouvelles, ce qu’il fait auprès du Comité d’instruction publique, puis du Premier Consul. Si La Grande Période est l’ouvrage singulier d’un auteur qui n’a joué aucun rôle majeur dans l’histoire des sciences, elle témoigne de la permanence de la demande sociale à laquelle Delormel s’est efforcé de répondre. Le désir d’unité qu’il exprime et auquel il entend contribuer est l’une des principales lignes de force politique et littéraire de la période révolutionnaire.In La Grande Période, published in 1790, 1796 and 1805, Jean Delormel defends the idea that the inclination of the Earth’s axis of rotation is slowly decreasing and that, consequently, humanity is advancing very slowly towards a new golden age. His theory presents three paradoxes: while time is both progressive and cyclical, progress is also both very slow and very fast as well as made up of happy and unhappy events and, consequently, the French Revolution can be one or the other, depending on the context of publication. Delormel defends the social usefulness of a theory of harmony that should give rise to hope and that can have concrete applications. Although it is based on astronomy and relies on elements of the biblical tradition, his science is a practical science that operates in two ways: by simplifying and by reconciling. The theorist of harmony is thus presented as the one who overcomes quarrels and provides the means to extinguish them. Writing for concord and progress, he can offer his services to the new institutions, which he does with the Committee of Public Instruction, then with the First Consul. If La Grande Période is the singular work of an author who played no major role in the history of science, it testifies to the permanence of the social demand to which Delormel tried to respond. The desire for unity that he expresses and to which he intends to contribute is one of the main political and literary key elements of the revolutionary period

Une éducation à la campagne : politique des Maîtres sonneurs

National audienceDans son roman Les Maîtres sonneurs, George Sand explore plusieurs scénarios éducatifs, en lien avec les débats de son temps sur la petite enfance

Finir la Révolution par l’éloge

Dans les mois qui suivent le coup d’État du 18 brumaire an VIII (9 novembre 1799), Napoléon Bonaparte installe son pouvoir. L’enjeu pour lui est que ce coup d’État, qui s’ajoute à beaucoup d’autres coups d’État, soit le dernier, c’est-à-dire que la Révolution soit terminée. Cela passe par l’efficacité de la police, par des succès militaires – ceux du printemps 1800 sont déterminants – mais aussi par des discours : par ce qui se dit et s’écrit à son sujet. Le nouveau pouvoir mène une politique..

Un 14 juillet de combat

Les livres d’Éric Vuillard racontent de grands effondrements comme la chute de l’Empire inca (Conquistadors, 2009), les millions de vies broyées par la Grande Guerre (La Bataille d’Occident, 2012) ou encore les derniers temps de la conquête de l’Ouest et le devenir des Indiens rescapés des massacres (Tristesse de la terre, 2014). La conclusion de L’Ordre du jour (2017) donne la formule de cette entreprise littéraire : « On ne tombe jamais deux fois dans le même abîme. Mais on tombe toujours d..

Data assimilation in glaciology

International audienceIn this short paper, we will give one example of an inverse problem in glaciology. This problem is fairly simple to state: how to infer a climatic scenario (i.e. how to reconstruct past polar temperature) from ice volume records? The idea of this work is to explore the ability of the adjoint method to solve the inverse problem of reconstructing past temperature given all available observations. We start here with a simplified ice-sheet model and perform twin experiments

Performance and applicability of a 2.5-D ice-flow model in the vicinity of a dome

This project is supported by the Université Grenoble Alpes in the framework of the proposal called Grenoble Innovation Recherche AGIR.Three-dimensional ice flow modelling requires a large number of computing resources and observation data, such that 2-D simulations are often preferable. However, when there is significant lateral divergence, this must be accounted for (2.5-D models), and a flow tube is considered (volume between two horizontal flowlines). In the absence of velocity observations, this flow tube can be derived assuming that the flowlines follow the steepest slope of the surface, under a few flow assumptions. This method typically consists of scanning a digital elevation model (DEM) with a moving window and computing the curvature at the centre of this window. The ability of the 2.5-D models to account properly for a 3-D state of strain and stress has not clearly been established, nor their sensitivity to the size of the scanning window and to the geometry of the ice surface, for example in the cases of sharp ridges. Here, we study the applicability of a 2.5-D ice flow model around a dome, typical of the East Antarctic plateau conditions. A twin experiment is carried out, comparing 3-D and 2.5-D computed velocities, on three dome geometries, for several scanning windows and thermal conditions. The chosen scanning window used to evaluate the ice surface curvature should be comparable to the typical radius of this curvature. For isothermal ice, the error made by the 2.5-D model is in the range 0-10ĝ % for weakly diverging flows, but is 2 or 3 times higher for highly diverging flows and could lead to a non-physical ice surface at the dome. For non-isothermal ice, assuming a linear temperature profile, the presence of a sharp ridge makes the 2.5-D velocity field unrealistic. In such cases, the basal ice is warmer and more easily laterally strained than the upper one, the walls of the flow tube are not vertical, and the assumptions of the 2.5-D model are no longer valid.Publisher PDFPeer reviewe

Geothermal flux and basal melt rate in the Dome C region inferred from radar reflectivity and heat modelling

Abstract. Basal melt rate is the most important physical quantity to be evaluated when looking for an old-ice drilling site, and it depends to a great extent on the geothermal flux (GF), which is poorly known under the East Antarctic ice sheet. Given that wet bedrock has higher reflectivity than dry bedrock, the wetness of the ice–bed interface can be assessed using radar echoes from the bedrock. But, since basal conditions depend on heat transfer forced by climate but lagged by the thick ice, the basal ice may currently be frozen whereas in the past it was generally melting. For that reason, the risk of bias between present and past conditions has to be evaluated. The objective of this study is to assess which locations in the Dome C area could have been protected from basal melting at any time in the past, which requires evaluating GF. We used an inverse approach to retrieve GF from radar-inferred distribution of wet and dry beds. A 1-D heat model is run over the last 800 ka to constrain the value of GF by assessing a critical ice thickness, i.e. the minimum ice thickness that would allow the present local distribution of basal melting. A regional map of the GF was then inferred over a 80 km  ×  130 km area, with a N–S gradient and with values ranging from 48 to 60 mW m−2. The forward model was then emulated by a polynomial function to compute a time-averaged value of the spatially variable basal melt rate over the region. Three main subregions appear to be free of basal melting, two because of a thin overlying ice and one, north of Dome C, because of a low GF

Ça ira de A à Z

International audienceAbécédaire à propos de la pièce de Joël Pommerat, Ça ira (1) Fin de Louis. Les entrées traitées sont les suivantes :A. Ah bon.B. Billard.C. Citations.D. Direct (effet de).E. Écrits.F. Fin.G. Genre/femme(s).H. Hors-scène (effets de).M. Micro.N. Noms.P. Perruques.Q. Quatorze Juillet.U. Urgence.V. Vote.Z. Zizanie

La Femme grenadier: Édition critique

International audienceÉdition critique de La Femme Grenadier, roman de Marie Armande Jeanne Gacon-Dufour, dont l'édition originale a été publiée en 1801

Report from the BfR expert hearing on practicability of hormonal measurements: recommendations for experimental design of toxicological studies with integrated hormonal end points

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