A Missed Connection

My point of departure will be two memoirs submitted to the French Académie Royale des Sciences, one in 1771, the other in 1772. The first dealt with an observation of an impressive fireball meteor s1 J. B. LeRoy, 'Mémoire sur le Météore ou Globe de Feu, Observé au mois de Juillet dernier dans une grande partie de la France', Histoire et Mémoires de l'Académie Royale des Sciences de Paris, 1771 (Paris, 1774), partie 'Memoires', 668-92. (Hereafter H.MA)RSP, the second with the chemical analysis of a stone alleged to have fallen from the sky s216. A. D. Fougeroux, L.-C. Cadet and A. Lavoisier, 'Rapport... d'une observation communiquée par M. l'Abbé Bachelay, sur une pierre qu'on prétend être tombée du Ciel pendant un orage', Introduction aux Observations sur la Physique, sur l'Histoire Naturelle, et sur les Arts, Vol. 2 (1777), 251-55. This is apparently a reprint of an article which appeared in Observations sur la Physique (July 1772), which I have so far been unable to obtain.. Both papers concerned things happening in the sky, and we know today that the two papers dealt with parts of the same phenomenon: the entry and fall of extraterrestrial bodies through the earth's atmosphere. Today such bodies are called 'meteors' while in transit through the earth's atmosphere, and 'meteorites' if they fall to the ground. At the time, however, no connection was made between these two phenomena, and in spite of the close proximity of the two papers in time, their subjects were not related to each other by the Académiciens. Nor were the two phenomena treated equally. While the report of the meteor treated it as a real event, that of the meteorite treated it as a fiction, or at least as some other kind of event which had been badly perceived: stones simply did not fall from the sky.

The failure to make a connection between these two phenomena was very serious, since the explanation of meteors was not possible without the evidence offered by the meteorite. LeRoy, the author of the paper on the meteor, felt that 'Among the multitude of objects of all sorts which physics encompasses, there are none of them more important, or which merit our attention more, than meteors s3LeRoy, op. cit. note 15, 668.. But he was no more able to offer a satisfactory explanation of them than had other savants. Edmund Halley, for instance, suggested in one article that they were solid bodies - and then, in another article five years later, that they were caused by the ignition of long trains of gas in the atmosphere s4 E. Halley, 'An Account of Several Extraordinary Meteors or Lights in the Sky', Philosophical Transactions of the Royal Society of London, Vol. 29, No. 341 (October-December 1714), 159-64; and 'An Account of the extraordinary METEOR seen all over England, on the 19th of March 1718/9. With a demonstration of the uncommon Height thereof', ibid., Vol. 30, No. 360 (April-May 1719), 978-90. (This journal will be referred to below as Phil. Trans.). LeRoy himself considered several hypotheses, but was unwilling to accept any of them as convincing. He did not seem to be aware of any reports of falling stones, and did not agree with the suggestion that solid bodies might be the cause of these appearances s5 LeRoy, op. cit. note 15, 680.. The clues which would have allowed the solution to the mystery were not seen as such.

And yet the clues existed. The stimulus for the 1772 chemical analysis had been three 'thunderstones' submitted to the Académie in 1769 from independent sources. The historian of the Académie even remarked upon the surprising resemblance of the stones to each other s6'Trois faits singuliers du meme genre', HMARSP, 1769 (Paris: 1772), partie 'Histoire', 20-21. For reasons that are not clear, the analysis in 1772 (see note 16) dealt with only two of the stones.. But the report of the chemical analysis of one of the stones, submitted by Fougeroux,. Cadet, and the great Lavoisier, concluded that the stones had not fallen from the sky. They remarked that 'true physicists' had always regarded the existence of such stones as very doubtful s7 Fougeroux et al., op. cit. note 16, 251., and they saw no reason in the chemical analysis of the stone at hand to change this opinion. This instance was merely one of many rejections which similar stones had to suffer at the hands of savants and learned academies. Because these crucial bits of evidence were rejected, understanding the nature of meteors would have to wait until after the appearance of Chladni's book in 1794.

It is interesting to note that the acceptance of one part of the phenomenon (meteors) and the rejection of the other (meteorites) rested upon unequal opportunities to observe the two. Whereas the meteor was often visible over several thousand square miles, the fall of the meteorite was visible only in a much more restricted area. This inequality meant that while commoners and savants alike might observe the meteor, and in great numbers, the number of witnesses to a meteorite fall was likely to be very small and was unlikely to include those with scientific training. In at least one case (Barbotan in 1790) the sighting of a meteor was readily accepted while savants rejected the fall of the meteoric stones which took place at the end of its path s8P. Bertholon, 'Observation d'un globe de feu', Journal des Sciences Utiles, Vol. 4, No. 24 (1791), 224-28.. During the eighteenth century, while articles on meteors either simply reported observations or dealt with possible explanations of their nature, the articles on meteorites were largely concerned with whether such things could actually fall from the sky.

Toward the end of the eighteenth century, this attitude began to change rapidly. In 1794 Chladni published his book, in which he used accounts of meteorite falls and finds to connect meteors with meteorites and suggested that the phenomena were of extraterrestrial origin. Shortly thereafter, as a sequel to several notable falls, the English chemist Howard and the emigre mineralogist de Bournon analyzed several meteoric stones and irons and found surprising similarities in their chemical composition. The iron meteorites contained nickel - a combination known to occur only in these 'rocks' fallen from the sky s9E. Howard and the Count de Bournon, 'Experiments and Observations on Certain Stoney and Metalline Substances, Which at Different Times are Said to Have Fallen on the Earth; Also on Various Kinds of Native Iron', Phil. Trans., Vol. 92 (1802), 168-212.. The chemical analyses went far toward convincing the savants of the reality of the phenomenon. In 1803, De Dree could remark that

It was not so long ago that one risked a disdainful smile by seeming to believe that mineral masses could fall from the atmosphere on to our globe; but thanks to the researches made by several savants on these extraordinary minerals, along with circumstantial accounts of the fall of some of them ... the general attention is now fixed on these astonishing phenomena s10 E. de Drée, 'Sur les masses minérales dites tombées de l'atmosphère sur notre globe', Journal de Physique, de Chimie, et d'Histoire Naturelle, Vol. 56 (April-May 1803), 380-89, citation at 380. (Hereafter J.PC)HN.

On the same day that these words were read before the Institut de France, it was announced that an enormous quantity of stones had fallen near the little town of l'Aigle, France, a mere 70 miles from Paris. Other reports followed; some of the actual stones arrived. The Institut sent Jean-Baptiste Biot to investigate. Biot, who had previously announced in favour of meteorites s11J.-B. Biot, 'Note sur des substances pierreuses d'une nature particulière, que l'on assure être tombées sur la terre', Bulletin des Sciences de la Société Philomatique, No. 66 (August-September 1802), 159-60; and 'Sur les substances minérales pretendues tombées du ciel, et nouvellement analysées par MM. Howard et Bournon', ibid., No. 68 (October-November 1802), 153-56., did a thorough and elegant job of investigation. His report n1 J. -B. Biot, Relation d'un Voyage fait dans le département de l'Orne pour constater la réalité d'un météore observé à l'Aigle le 26 Floréal an 11 (Paris: Baudouin, 1803). (Note: the date given in the title is in error. It should be 6 Floréal, or 26 April 1803, as the text of the book shows), put to rest virtually all the remaining doubts about the reality of meteorites.