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Magellan, Jean-Hyacinthe (Magalhães, Jo


(b. Aveiro, Portugal, 4 November 1722; d. Islington, England, 7 February 1790)

chemistry, physics, scientific instrumentation.

Little is known about Magellan’s youth and early manhood. His family, who made an unproven claim to be descended from Ferdinand Magellan, sent him to an Augustinian monastery in Coimbra when he was eleven years old, and there he lived and studied for about twenty years, first as a novice and then as a monk. There was a scientific tradition among the Coimbra Augustinians (it is reported that they studied the works of Newton), and as a consequence Magellan became well enough versed in astronomy to serve as a guide for, and to gain the friendship of, Gabriel de Bory during the latter’s visit to Portugal in 1751 to observe a solar eclipse. A few years later Magellan sought and received permission from Pope Benedict XIV to leave the order. From 1755 to about 1764, Magellan traveled through Europe, finally settling in England, where he resided for the rest of his life. At some point he was converted to Protestantism. He never married.

Magellan produced no scientific work of serious consequence. He did, however, find ways to meet or to write to everyone whose activities interested him, and, as a result, is known chiefly for his wide circle of acquaintances and for acting as an intermediary in disseminating new information. He introduced English scientific instruments into France, edited Cronstedt’s Mineralogy, and informed the French chemists of Priestley’s work. He was a fellow of the Royal Society and a member of several European academies of science. Industrial spy, indefatigable learner of languages, shameless borrower from others’ writings, Magellan nevertheless showed little of that malice usually associated with the gossip or the hangeron. A curious mixture of unoriginality and independence, he had no great ambitions for himself.

Magellan wrote more about scientific instruments than about any other subject. His first work (1775), a description of English octants and sextants of the reflecting or Hadleyan type, was clearly written, detailed, and useful. He also wrote on barometers and other meteorological instruments (although not always with full understanding), 1 and on Atwood’s machine. These works were all in French, in keeping with Magellan’s role as correspondent of the Academy of Sciences, as agent of Trudaine de Montigny (intendant of finances), and as bearer of good news to the Continent from the land of the artisan-scientist coalition.2

Through his reading, correspondence, and acquaintances, Magellan kept up with the latest developments in English, Scottish, and Swedish chemistry and experimental physics. His work on “elementary fire” helped to disseminate the new theories of heat being worked out by Black, Irvine, and Crawford, and introduced the term “specific heat” (chaleur spécifique) into the language. It also gave the first published table of specific heats, although these were derived from determinations by Richard Kirwan.3 Magellan early saw how important were the investigations of Priestley, whose good friend he became, and his characteristic response to Priestley’s fundamental research was twofold: he told the French about it, and he produced a pamphlet describing some small improvements in the apparatus for making carbonated water and some refinements in the construction of nitric oxide eudiometers.4

Gustav von Engestrom, who had studied mineralogy with Cronstedt, was Magellan’s link with Swedish chemistry. Engestrom translated into English, at Magellan’s behest, the Mineralogy of Cronstedt (1770). Magellan undertook to publish a second edition, which was to have notes by Giovanni Fabbroni and Kirwan; but by the time he was ready, Kirwan’s own Mineralogy had appeared (1784). Magellan went ahead, and, to Kirwan’s great annoyance, 5 borrowed from him where appropriate, and also incorporated recently published findings of Bergman, Scheele, A. Mongez, and M. T. Brünnich. Although he “rearranged” the text to include new developments, Magellan was convinced that much in Cronstedt’s system was still valuable. He especially endorsed the latter’ combinations of chemical analysis with the observation of the external characteristics of minerals.6

In his notes to Cronstedt, Magellan gave a good picture of conventional contemporary thinking about the foundations of chemistry. Thus various bodies, he said, although suspected of being compound, “may and even ought to be considered as primitive substances with respect to our knowledge of them, till they shall be experimentally decomposed.”7 Acid and alkaline substances act on other bodies in virtue of an “attraction,” about which Magellan says:

We may complain indeed of the deficiency of our knowledge in regard to the essential cause of this phenomenon which we mean to explain by the word attraction; but it being the ultimate effect our knowledge can reach to, after our observation has been driven from cause to cause of all that we can discern in nature, we must rest contented with the simple deductions from such an evident and general principle, whatever may be its original cause.8

Magellan also shared the widespread belief that the smallest bit of a chemically reacting substance is some sort of basic unit, and asserted at one and the same time that these smallest parts probably possess polarity, and that we know nothing whatever about them.9 As Magellan’s editing proceeded, the notes on Lavoisier’s new theory of combustion and calcination increased,10 until finally Magellan conceded to the arguments in the Nomenclature (1787). He retained the old language of the phlogiston theory for the remainder of the work, however, remarking, “ut pes et caput uni reddantur formae, according to the old adage of Horace.”


1. See W. E. K. Middleton, A History of the Barometer (Baltimore, 1964), 102–104, 114, 122–123,259–260, 377;and Invention of the Meteorological Instruments (Baltimore, 1969), 79, 146.

2. See Birembaut, cited below, and M. Daumas, Les instruments scientifiques aux xviie et xviiie siècles (Paris, 1953), 138 ff.

3. Robert Fox, The Caloric Theory of Gases (Oxford, 1971), 26–29.

4. The story of Magellan’s role in the introduction to France of Priestley’s discoveries ha been masterfully reconstructed in ch. 2 of Guerlac, cited below.

5. See the summary of Kirwan’s letter (1788)to Banks in W. R. Dawson, ed., The Banks Letters (London, 1958), 493.

6. Cronstedt’s Mineralogy I, v-x.

7.Ibid., p. 263 n; the work is continuously paginated.

8.Ibid., p. 328 n.

9.Ibid., pp. 428–431 n.

10.Ibid., notes on pp. 285, 435 ff., 431–432, 444–445, 447, and 491–493, for example.


I. Original Works. Among Magellan’s works are Description des octants et sextants anglois … (Paris-London, 1775); Description of a Glass Apparatus, for Making Mineral Waters Like Those of Pyrmont, Spa, Seltzer … Together With the Description of Some New Eudiometers … in a Letter to the Rev. Dr. Priestley (London, 1777; 2nd ed.,rev., 1779; 3rd ed., enl., 1783), German trans. by G. T. wenzel (Dresden, 1780); Description des nouveaux instruments à reflection pour observer avec plus de précision les distances angulaires sur mer … (London, 1779); Collection de différents traités sur des instruments d’astronomie, physique… (Paris-London, 1775–1780); Description et usages des nouveaux baromètres, pour mésurer la hauteur des montagnes et la profondeur des mines … (London, 1779); Description et usages des instrumens d’asronomie et de physique faits à Londres, par order de la cour de Portugal en 1778 et 1779 … (London, 1779); Notice des instrumens d’astronomie, de géodésie, de physique, etc., faits dernièrement à Londres par ordre de la cour d’Espagne … (London, 1780); Description d’une machine nouvelle de dynamique inventée par M.G.Atwood, au moyen de laquelle on rend trés aisement sensible les loix du mouvement des corps en ligne droite, et en rotation… (London, 1780); and Essai surela nouvelle théorie du feuélémentaire, et de la chaleur des corps … (London, 1780).

Magellan contributed to A.G. Lebégue de Presle, Rélation ou notice des derniers jours de J.J.Rousseau … avecune addition relative au méme sujet, par J.H. Magellan (London-Paris, 1778). He edited A.F. Cronstedt, An Essay Towards a System of Mineralogy, 2 vols. (London, 1781; 2nd ed., 1788); and Voyages et mémoires de Maurice-Auguste, Comte de Benyowski sur la Pologne, 2 vols. (Paris, 1791). He also published a number of articles in the Journal de physique between 1778 and 1783.

II. Secondary Literature. For works about Magellan, see Arthur Birembaut, “Sur les letters du physicien Magellan conservées aux Archives Nationales” in Revue d’histoire des sciences et de leurs applications, 9 (1956), 150–161; J.-P. Brissot, “Mémoires (1754–1793),” in C.Perroud, ed., Mémoires et documents relatifs aux XVIII et XIX siècles, I (Paris, 1911), 362–363; Joaquim de Carvalho, “Correspondência cintifica dirigida a João Jacinto de Magalhães,” in Revista da Faculdade de ciências, Universidade de Coimbra20 (1951),93–283 and also published separately (Coimbra, 1952); Henry guerlac, Lavoisier: The Crucial Year (Ithaca, N.Y.,1961), esp. ch.2; John Nichols, Literary Anecdotes of the Eighteenth Century, VIII (London, 1814), 48–51n, and Alexandre Alberto de Sousa Pinto, A vida e a obra de João Jacinto de Magalhães (Pôrto, 1931).

Stuart Pierson

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