Jean-Baptiste Biot and L’Aigle Meteorite in 1803

Jean-Baptiste Biot was a French physicist, astronomer, and mathematician who had a fascination with meteorites. A year before the birth of the English novelist Jane Austen, Biot was born to a treasury official named Joseph Biot on 21 April 1774. Like many other Frenchmen, Biot was educated at the École Polytechnique, a prestigious school founded by Lazare Carnot and Gaspard Monge, during the French Revolution.

Part of the reason Jean-Baptiste Biot became fascinated by meteorites was because stories about them seemed unbelievable. For instance, at Barbotan, in the South of France, inhabitants reported that they sought refuge in their houses after a hail of stones rained down upon them on the evening of 24 July 1790. Most of the people in the area did not believe stories about meteorites, even though some specimens of the stones from this shower were preserved in people’s private collections.

For those people who did not witness the hail of stones in Barbotan, they thought there was no way stones could fall from the sky unless they were a product of volcanic eruption. Others thought the stones somehow formed in the atmosphere or were created somehow by lightning. However, there were also some people who believed Ernst Chladni, a German physicist who published a book in 1794 stating that the stones that fell from the sky were extraterrestrial. His reasoning made an impression on some people, but many still failed to agree as to where the stones originated or how they might fall from the sky. It seemed as if the question would never be solved until a meteor shower occurred on 26 April 1803.

That was when Jean-Baptiste Biot found a chance to prove the origins of the stones because thousands of “stones” fell upon L’Aigle. The shower stirred up so much interest, he was sent by the Academy of Sciences to investigate and was tasked with determining once and for all the origins of these falling stones. Thus, he left Paris on 5 June and traveled from Paris to Alencon, a large town about fifteen leagues away from L’Aigle.

When Jean-Baptiste Biott reached Alencon, he made his first inquiries as to what witnesses saw and heard during the “dreadful shower of stones.”[1] From Alencon to L’Aigle, the account was the same. He found that he had plenty of witnesses who repeated similar stories. He also learned that a “globe of fire” was seen about 1pm and afterwards, a violent explosion discharging a shower of stones. It lasted for about six minutes and was heard over a large extended area. Some witnesses described the sound as if a “heavy railroad train” punctuated by cannon-like booms.

“At L’Aigle … he found in the fields for nearly two square leagues, a great quantity of meteoric stones, which differed entirely from the mineralogical stones in the neighbourhood, or from any that had ever been seen in that part of the country. Some of them weighted fifteen pounds, and all of them, upon being broken, emitted a strong sulphureous smell. The stones themselves, together with the concurrent testimony of all ranks of the inhabitants in the neighbourhood, … put the fact beyond dispute.”[2]

When the meteor shower occurred, it was reported to be much like a shooting star, except far more brilliant. It was also said to sound like a “heavy railroad train” or a “rushing roar.” The stones that fell hit rooftops, trees, and pavements. Only one injury was reported and that was person a wounded in the arm. However, several people thought their chimneys were on fire when the storm began, and they rushed outside to get a pail of water only to discover there was no fire. Regarding the shower, it was reported:

“The number that fell cannot have been less than two to three thousand. It has been stated that some of these were very friable for some days after they had fallen, and that they had a strong sulphurous smell, which partially disappeared as the stone became harder, but was retained for a long time, and manifested itself afterwards when any of the stones were broken.”[3]

Many newspapers reported on the exciting event. Among those was the following article reprinted in the Edinburgh Magazine:

“From the evidence adduced, it appeared that a fire-ball, moving to the south had been observed, followed by a violent explosion. The phenomenon seemed to be connected with a small cloud of rectangular form to the N.N.W. of L’Aigle at a considerable altitude. A hissing noise was heard over the entire canton, and an amazing number — nearly three thousand — of meteoric stones descended. It was observed that the direction of the shower was exactly in the line of the magnetic meridian. These masses were projected over an elliptic surface of twenty-five leagues in length and one in breadth; the largest weight seventeen pounds.”[4]

Biot’s investigation was considered very interesting at the time because of his groundbreaking approach and methodical methods described a follows:

“He first ascertains the mineralogical structure of the spot where the stones have been found, and finds that in no respect is there any faint approach to substances such as physical and chemical investigation proves these stones to be. He then examines the testimony of those who saw the meteor, and those who heard its explosion. Instead of going at once to the spot where the meteor is said to have fallen, he begins by drawing a circle of some miles round it, and compares the testimony of those living at a distance with those living on the spot; by this means he finds a remarkable uniformity as to time and circumstance — points on which the testimony of men who were inventing or were deluded, would necessarily differ.”[5]

After gathering witness testimonies and collecting some 2,000 specimens, Jean-Baptiste Biot returned to Paris. There he wrote a lengthy report that detailed his findings and sent a copy of it to the Minister of the Interior. Because of Biot’s report it was thus concluded:

“Inasmuch as peasants, women, children, priests, and soldiers in a circle of ten miles, all concur as to the main facts of time and circumstance, — and as this testimony is supported by the presence of the stones said to have fallen, and by the nature of these stones, which are totally unlike anything to be found in the district, and are like other meteoric stones said to have fallen elsewhere — the conclusion is inevitable.”[6]

Biot’s report clearly demonstrated that the stones originated from an extraterrestrial source. He was convincing because he had so many first-hand testimonies and had done such a thorough investigation. Moreover, only after Jean-Baptiste Biot analyzed the rocks at L’Aigle did it become commonly accepted that the fireballs seen in the sky were meteors falling through the earth’s atmosphere and not something else.

References:

• [1] Phipson, Thomas Lamb, Meteors, Aerolites, and Falling Stars, 1867, p. 39.
• [2] “Natural Phenomena,” in Tyne Mercury; Northumberland and Durham and Cumberland, 30 August 1803, Gazette, p. 4.
• [3] Phipson, p. 40.
• [4] Tait, William, Tait’s Edinburgh Magazine, 1856, p. 401. 
• [5] The Practical Philosopher at Work, in Manchester Weekly Times and Examiner, 24 December 1858, p. 10.
• [6] Blackwood’s Edinburgh Magazine, Volume 84, 1858, p. 677.