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Bill Thayer

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Home This webpage reproduces an article in the

Transactions of the American Philosophical Society

Vol. 6 (1802), p25 The text is in the public domain. This page has been carefully proofread

and I believe it to be free of errors.

If you find a mistake though,

please let me know!

p25 Description of a singular Phenomenon

seen at Baton Rouge, by William Dunbar, Esq.

communicated by Thomas Jefferson, President A. P. S.a

Natchez, June 30th, 1800

Read 16th January 1801.

A phenomenon was seen to pass Baton Rouge on the night of the 5th April 1800, of which the following is the best description I have been able to obtain.

It was first seen in the South West, and moved so rapidly, passing over the heads of the spectators, as to disappear in the North East in about a quarter of a minute.

It appeared to be of the size of a large house, 70 or 80 feet long and of a form nearly resembling Fig. 5 in Plate IV.b

It appeared to be about 200 yards above the surface of the earth, wholly luminous, but not emitting sparks; of a colour resembling the sun near the horizon in a cold frosty evening, which may be called a crimson red. When passing right over the heads of the spectators, the light on the surface of the earth, was little short of the effect of sun-beams, though at the same time, looking another way, the stars were visible, which appears to be a confirmation of the opinion formed of its moderate elevation. In passing, a considerable degree of heat was felt but no electric sensation. Immediately after it disappeared in the North East, a violent rushing noise was heard, as if the phenomenon was bearing down the forest before it, and in a few seconds a tremendous crash was heard similar to that of the largest piece of ordnance, causing a very sensible earthquake.

I have been informed, that search has been made in the place where the burning body fell, and that a considerable portion of the surface of the earth was found broken up, and every vegetable body burned or greatly scorched. I have not yet received answers to a number of queries I have sent on, which may perhaps bring to light more particulars.

Note. The above communication was accompanied by an account of the first invention of the Telegraphec extracted from the works of Dr. Hook. Mr. Dunbar was induced to forward this extract to the Society, as he supposed it had been less noticed than it deserved to be. But it was deemed unnecessary to print the Paper, as it may be seen in the works above mentioned, and is referred to by Dr. Birch in his history of the Royal Society. Vol. 4th, page 299.

Thayer's Notes:

a Thomas Jefferson, who at the time of this report was Vice-President of the United States, and would become President not much later. Several other items from William Dunbar were also passed along to the American Philosophical Society by Jefferson and included in the same issue of the Transactions. Dunbar, a resident of Natchez, was a tireless investigator of natural phenomena of the lower Louisiana, at the time still Spanish territory: rainfall, winds, rainbows, fossils, the Mississippi delta; he also writes of sign language among the native peoples in the area.

At the time this note was read, the existence of meteorites was a hotly debated topic, and it was not until 1803 with Jean-Baptiste Biot's report of the fall of a meteor near the Norman town of L'Aigle that scientific opinion accepted that things do fall out of the sky; had Baton Rouge been in densely populated Europe where the terrain made investigation much easier, Dunbar and not Biot might have been the man whose name would attach to the history of meteoritics. On the other hand, the same issue of the Transactions includes several notes explicitly discussing meteors and meteoric stones — but this is not one of them. So: keep on reading. . . .

b I've been unable so far to find any trace of the Plate, much to my regret. I suspect it was part of Dunbar's fuller communication (see Jefferson's note) and was left on the cutting room floor, so to speak.

More importantly, if the observation of the object's size is anywhere near accurate, it was not a meteorite: an object of this size, entering earth's atmosphere at a speed typical of objects falling to earth from space, would probably have left a much larger trace of itself, and would almost certainly have killed the observer and anyone else near the fall. Scientists currently gauge the size of the iron meteor that created Arizona's Meteor Crater, for example, at roughly 50 meters, only about twice the estimate reported by Dunbar.

Further confirmation that this was no meteorite seems to be given by the object's speed. Assuming more or less flat terrain (and though the vicinity of Baton Rouge is considered hilly by Louisiana standards, the State is one of the flattest in the Union and this area is at most gently rolling) and an observer whose eyes were a bit more than 1.50 meters above the ground the horizon is about 4.4 km away. The distance covered by the object within the witnesses' field of vision was thus a maximum 9 kilometers, but probably only about two-thirds of that (since they surely didn't notice it the instant it rose over their horizon, although once they saw it, they must with equal certainty have tracked it to the very end). If, then, it covered 6 to 9 km in something like 15 seconds, it was traveling at no more than 2200 km an hour. This is considerably less than the 11,000 km/h minimum impact velocity of an object freefalling to Earth from space. Furthermore, if we can trust Dunbar's witnesses on the height of the object above the ground, and as he explicitly states, directly above their heads — yet such perceptions of distance against a featureless sky are notoriously subject to error, even among trained pilots — its trajectory must have been far flatter than that of any normal meteor: it was 200 m above the ground and continued to travel at least 6 km (to the horizon, then "a few seconds") before it crashed, an angle of at most 1.9°. He speaks of it, at any rate, as on a more or less level trajectory.

The vague language and third-hand nature of the report on the débris field are regrettable, but the impact damage and the seismic event are consonant with a small meteor — this handy-dandy calculator courtesy of the Lunar and Planetary Laboratory of the University of Arizona, backed up by some serious science, will be of interest to those of you wishing to input varying parameters — but also with a supersonic aerial craft of some kind. Inputting my own estimated parameters, most of them already given above,

Distance from impact: 6 km Projectile diameter: 75 feet Projectile density: porous stone: 1500 kg/m3

maybe a bit more if some kind of craft, i.e., a semi-hollow metal object Impact velocity: 0.6 km/s Impact angle: 1.9° Target type: Sedimentary rock

the model yields a seismic effect somewhat, but not much, less than that reported by the witnesses (who were almost certainly not knocked down, else we'd been told), and a 55‑decibel sound level, similarly less than that reported; more interestingly, a crater about 40 m wide and 8.7 m deep, and a transient crater depth of 11.6 meters, with the projectile landing "intact", and thus presumably lodged about 3 meters below the surface of the ground; get out your GPS and metal detectors, folks.

In a discussion online (here), two good points have been made: (a) at the range of speeds we're looking at here, there should have been a sonic boom in addition to the sound of any impact; and (b) Dunbar's estimate of the object's size, if it was on fire, is probably not so good: the most we can say is that it was no larger than a house. In turn, if it was a house-sized object coming in at a meteoric speed, it would have been a huge event, with no survivors for miles, flattened trees, etc. So of one thing we can be sure: if it was the size of a house, it crashed at a low speed; if it was a meteor, it was not the size of a house.

c Not Morse's telegraph, of course, some forty years in the future, but the optical telegraph of Robert Hooke (1635‑1703), or more likely in view of the near-French spelling of Telegraphe, that of Claude Chappe (late 18c, and thus pretty much the latest thing at the time this UFO report was written).