L’émergence contrariée du chronographe imprimant dans les observatoires français (fin 19e – début 20e s.)

Les observatoires occidentaux se transforment en véritable usine scientifique à partir du milieu du 19^e siècle. L'astrométrie symbolise ce passage à une économie industrieuse des pratiques scientifiques. Le chronographe imprimant, qui permet de réduire les équations personnelles des observateurs, s'impose, d'abord aux Etats-Unis, puis en Angleterre, en instrument-emblème de cette transformation profonde. En France, les initiatives de l'astronome Liais restent prototypiques. Ce n'est qu'au début du 20^e siècle, par les voies détournées de l'observatoire d'Hendaye et de l'abbé Verschaffel, que le chronographe imprimant fait son retour et conquiert les espaces savants. La centralisation excessive de l'astronomie française, l'autoritarisme du directeur de l'Observatoire de Paris Urbain Le Verrier, et la faiblesse du marché des instruments expliquent pourquoi le chronographe imprimant n'a fait souche que très tardivement en France.     

Instruments of Music,Instruments of Science: Hermann von Helmholtz's Musical Practices,his Classicism,and his Beethoven Sonata

The young Hermann Helmholtz, in an 1838 letter home, declared that he always appreciated music much more when he played it for himself. Though a frequent concert-goer, and celebrated for his highly influential 1863 work on the physiological basis of music theory, Die Lehre von den Tonempfindungen, it is likely that Helmholtz's enduring engagement with music began with his initial, personal experience of playing music for himself. I develop this idea, shifting the discussion of Helmholtz's work on sound sensation back to its origins, and examine the role of his material interaction with musical instruments and music itself. In his sound sensation studies, Helmholtz understood sound as an external, physical object. But Helmholtz also conceived of sound in musical terms. Further, Helmholtz's particular musical tastes as well as his deeply personal interaction with musical instruments allowed him to reconcile his conception of sound as physical object with his conception of sound as music. Helmholtz's physiological theory of sound sensation was both the product of and constitutive of how he heard and created sound. I argue that Helmholtz himself was the embodied reconciliation of his physiological theory of sound sensation and his belief that musical aesthetics were historically and culturally contingent.     

The introduction of the differential notation to Great Britain

In the history of chemistry, the Danish chemist Julius Thomsen (1826–1909) is best known for his contributions to thermochemistry. Throughout his life, he was a pronounced atomist and a tireless advocate of neo-Proutian views as to the constitution of matter. On many occasions, especially in his later years, he engaged in speculations concerning the unity of matter and the complexity of atoms. In this engagement, Thomsen was alone in Danish chemistry, but his works were representative of a large number of 19th-century chemists, particularly in England and Germany. Thomsen's ideas as to the constitution of matter, the periodic system and the noble gases, may be seen as typical of this vigorous trend in fin de siècle chemistry.     

Jean Méry (1645–1722) and his ideas on the foetal blood flow

We present an analysis, and first full English translation, of a paper by Kant entitled ‘Über die Vulcane im Monde’ (1785). Kant became interested in the question of whether the mountains of the Moon were extinct volcanoes. Stimulated by the work of Herschel, Aepinus, and others, he considered the appearance of the Moon's surface and the possibility of lunar vulcanism. From this, he was led to consider the structures of mountain ranges on the Earth, which he decided were non-volcanic in origin, being produced by eruptions of vapours from the interior of the Earth soon after it formed from an original ‘chaos’. Kant developed his ideas in such a way as to yield a characteristic eighteenth-century ‘theory of the Earth’. We argue that the empirical base of his theory was provided by knowledge of the mountain ranges of Bohemia and Moravia. Analogies based on observations of the Moon further assisted in the construction of the theory. But the reasoning ran in two directions: what was seen on the Moon was construed in terms of what Kant knew of the Earth's topography; and the Earth's topography was presumed to be analogous to that of the Moon, for both the Earth and the Moon (and indeed all heavenly bodies) supposedly had essentially similar origins. Kant's ideas of 1785 are related to his earlier writings of 1754, 1755, and 1756, and also to the lectures on physical geography that he presented at Königsberg.     

The Philosopher's conception of Mathesis Universalis from Descartes to Leibniz

In Descartes, the concept of a ‘universal science’ differs from that of a ‘mathesis universalis’, in that the latter is simply a general theory of quantities and proportions. Mathesis universalis is closely linked with mathematical analysis; the theorem to be proved is taken as given, and the analyst seeks to discover that from which the theorem follows. Though the analytic method is followed in the Meditations, Descartes is not concerned with a mathematisation of method; mathematics merely provides him with examples. Leibniz, on the other hand, stressed the importance of a calculus as a way of representing and adding to what is known, and tried to construct a ‘universal calculus’ as part of his proposed universal symbolism, his ‘characteristica universalis’. The characteristica universalis was never completed—it proved impossible, for example, to list its basic terms, the ‘alphabet of human thoughts’—but parts of it did come to fruition, in the shape of Leibniz's infinitesimal calculus and his various logical calculi. By his construction of these calculi, Leibniz proved that it is possible to operate with concepts in a purely formal way.     

James F. W. Johnston's influence on agricultural chemistry in the Netherlands

This paper describes the introduction of Liebig's ideas on agricultural chemistry into the Netherlands. The aversion to Liebig held by the Utrecht professor G. J. Mulder hindered the direct influence that might have been borne by Liebig's own writings; the introduction was made principally by means of Dutch translations of the text-books of the Scottish agricultural chemist J. F. W. Johnston, who generally followed Liebig's ideas.     

Hypothesis and experiment in the early development of Kekulé's Benzene theory

This article attempts a contextual study of the origin and early development of August Kekulé's theory of aromatic compounds. The terminus a quo is essentially August Hofmann's coining of the modern chemical denotation of ‘aromatic’ in 1855; the terminus ad quem is the first full codification of Kekulé's theory in the sixth fascicle of his Lehrbuch der organischen Chemie, published in the summer of 1866. Kekulé's theory is viewed in context with the earlier and concurrent experimental work of such chemists as Hermann Kolbe, Friedrich Beilstein, Rudolph Fittig, and Hugo Müller. The reception of the theory is briefly examined. Attention is paid to the role of Kekulé's molecular models and of his celebrated dream anecdote of the snake that seizes its own tail. The episode is used as a case study for the continuity of scientific progress, and to illustrate the close reciprocal interactions of hypothesis and experiment in the evolution of a scientific theory.