Titre complèt: La Chaleur considérée comme un mode de mouvement

La Chaleur, Mode de Mouvement...

Extrait:Qu'est - il donc et comment le caractériserons-nous? En disant qu'il est tout à la fois, dans son unité merveilleuse, élémentaire et supérieur, physique et mathématique, expérimental et rationnel; qu'il constitue un mode d'enseignement sui generz's, analytique et synthétique à la fois, vraiment nouveau et admirable en soi.

La Lumière: Six leçons faites en Amérique dans l'hiver de 1872-1873

The oldest historic reference to the rainbow is known to all: "I do set my bow in the cloud, and it shall be for a token of a covenant between me and the earth... And the bow shall be in the cloud; and I shall look upon it, that I may remember the everlasting covenant between God and every living creature of all flesh that is upon the earth."

To the sublime conceptions of the theologian succeeded the desire for exact knowledge characteristic of the man of science. Whatever its ultimate cause might have been, the proximate cause of the rainbow was physical, and the aim of science was to account for the bow on physical principles...

The condition requisite for their production is, that the drops which constitute the shower shall all be of nearly the same size. When the drops are of different sizes, we have a confused superposition of the different colors, an approximation to white light being the consequence. This second step in the explanation of the rainbow was taken by a man the quality of whose genius resembled that of Descartes or Newton, and who eighty-two years ago was appointed Professor of Natural Philosophy in the Royal Institution of Great Britain. I refer, of course, to the illustrious Thomas Young.

Explanation of the Rainbow

It is so common a notion nowadays that electricity had its birth and rise in the nineteenth century that it gives one a strange mental sensation to contemplate the fact that all the myriads of commercial applications that have of late years been developed in this field might have been made by the Chinese or the ancient Egyptians, so far as the potentiality of Nature for developing electrical phenomena is concerned. The writer used to know a delightful old gentleman in Vermont who once referred, as to a well-known fact, to Edison's having invented electricity. It is astonishing how closely his state of mind typifies that of a great many people.

In the form of the lightning, the aurora, and the shock of the electric eel or torpedo, electrical manifestations have been known ever since man commenced to observe those phenomena, but the fossil resin amber was the substance which eventually gave its name to the now tremendous agency. This material was observed, many centuries before our era, to possess the property of attracting light bodies to itself when rubbed with wool, and, being called electron by the Greeks, transmitted its name to the property or force which it thus brought into evidence. The fact is mentioned as early as 600 B. C, by Thales of Miletus, although he does not transmit to us the name of the original observer of the phenomenon. Homely as was the experiment, it marked a beginning in electrical research.

Electricity : from Thales to Faraday

Extrait:Ces leçons élémentaires sur la chaleur et le froid sont une improvisation savante et heureuse, recueillie par un sténographe exercé,et dont l'éminent professeur a autorisé la publication, non sans une certaine hésitation. Loin de remplacer le beau traité sur la chaleur, que je suis fier d'avoir traduit, et qui a eu un si grand retentissement, elles le feront ardemment désirer et le rendrout comme nécessaire à tous les amis du progrès. Je les publie d'abord parce qu'elles contribueront efficacement à populariser une grande somme d'idées neuves, saines et fécondes en second lieu, parce qu'un petit volume, à prix réduit, sur cette matière si importante, qui puisse être donné en récompense a leurs élèves, m'était instamment demandé par un grand nombre de professeurs de lycées, colleges, institutions, etc. Si je ne me fais pas illusion, à force d'étude et de patience, je suis parvenu à rendre la lecture de ces leçons facile et agreable. La traduction a été ébauchée en partie par M. L'abbé Baillard, en partie par M. Auguste Guiot, docteur en sciences; qu'ils acceptent mes remerciments.

Chaleur et Froid: Six leçons faites devant un jeune auditoire pendant les vacances de Noël 1867

"The feelings and aims with which Newton and Goethe respectively approached Nature were radically different, but they had an equal warrant in the constitution of man. As regards our tastes and tendencies, our pleasures and pains, physical and mental, our action and passion, our sorrows, sympathies, and joys, we are the heirs of all the ages that preceded us; and, of the human nature thus handed down, poetry is an element just as much as science. The emotions of man are older than his understanding, and the poet who brightens, purifies, and exalts these emotions, may claim a position in the world at least as high and as well-assured as that of the man of science. They minister to different but to equally permanent needs of human nature; and the incompleteness of which I complain consists in the endeavor on the part of either to exclude the other. There is no fear that the man of science can ever destroy the glory of the lilies of the field; there is no hope that the poet can ever successfully contend against our right to examine, in accordance with scientific method, the agent to which the lily owes its glory. There is no necessary encroachment of the one field upon the other. Nature embraces them both, and man, when he is complete, will exhibit as large a toleration."

Goethe's Farbenlehre : Theory of Colors

Enfin, mon ami, me voici bien loin de la fumée et du tumulte de Londres ; le ciel est bleu au-dessus de moi et le Rhin s'étend en nappes brillantes sous ma fenêtre. Le fleuve étincelant coule rapide et silencieux ; ici il ne laisse échapper aucun murmure, mais plus haut il se heurte et se brise en écume contre les piles d'un pont ; ses ondes bouillonnantes s'élancent en gerbes élastiques et ébranlent l'air de vibrations sonores. Ainsi la force mécanique violente du fleuve se transforme en musique.

Fruit d'une sélection réalisée au sein des fonds de la Bibliothèque nationale de France, Collection XIX a pour ambition de faire découvrir des textes classiques et moins classiques dans les meilleures éditions du XIXe siècle.

La Chaleur, Mode de Mouvement...

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