Conception : la grande boule de feu du 9 Février 1913

C. A. Chant (1913a), dans un rapport de 71 pages, donne un récit détaillé de l'apparition météoritique spéctaculaire du 9 Février 1913. La série de bolides en désintégration passa de Saskatchewan ESE au-dessus des Grands Lacs et au-dessus de la côte du New Jersey. Plusieurs "vagues" d'objets en groupe furent observées, noise was heard at least 50 miles from the sub-bolide point, and ground shocks were reported. Other remarkable sporadic meteors were seen in various scattered locations around the world for a period of some days. Chant deduced that the height of the path, which followed the earth's curvature, was about 26 miles and that the geocentric velocity was in the range 5-10 miles/s. M. Davidson (1913) réanalysa les données de Chant, plus des observations depuis les Bermudes, et conclurent que l'objet avait une altitude de quelques 46 miles au-dessus de l'Ontario, et Chant (1913b) subsequently inferred that they reached perigee over Ontario, but were not destroyed, moving out into a new orbit when seen from Bermuda.

The phenomenon appeared rather like the Zond IV re-entry. It is well-described in the "extended extracts" from letters published by Chant. Clusters of stellar-like objects passed overhead, with tails several degrees long and accompanied by smaller, fainter objects. It is a subjective judgment, possibly influenced by some editing of the letters by Chant, that the 1913 reports are on the whole more objective than those of this decade. There are probably two reasons for this:

1. In 1913 la démarcation entre les personnes "éduquées", from whom Chant was likely to receive letters, and "uneducated persons," was greater.
2. In 1913, there was no widely known conception (i.e. pre-conception of mysterious saucer-shaped aircraft or spaceship (although several reports refer to the object as an airship). Further, the 1913 reports (as published) tend to be more descriptive; the word "meteor" is used in a non-generic sense simply to mean a bright object passing across the sky. There is little attempt among the correspondents to infer what the objects were.

Chant himself indicates that the reports varied in quality due to the process of conception and interpretation: The reader ... will ... . see that intelligent people can differ widely in describing a phenomenon, and will be able to appreciate the difficulty I have had in discriminating between very discordant observations. He presents reports of nearly 150 witnesses.

The "airship effect" is clearly present. Consider these reports:

1. The series of lights traveled in unison and so horizontal that I could think only of a giant flying machine. The lights were at different points, one in front, one further back, and a rear light, then a succession of small lights in the tail.
2. They ... did not seem to be falling as meteors usually do, but kept a straight course ... above the horizon. Our first impression was that a fleet of illuminated airships of monstrous size [was] passing. The incan- descent fragments themselves formed what to us looked like the illuminations while the tails seemed to make the frame of the machine. They looked like ships travelling in company.
3. The meteor resembled a large aeroplane or dirigible, with two tiers of lights strung along the sides.
4. The witnesses "reported that they had seen an airship going east. The heavens were brilliantly illuminated, and with the passage of the meteors a shower of stones was seen to fall. (This last element is not mentioned elsewhere and appears to be spurious.)
5. I took it for an aeroplane with both headlights lit, and as it came nearer the sparks falling behind it made it appear still more like one. However after a minute or a minute and a half I could see it was a meteor ... It was very low, apparently just above the hills.
6. My brother shouted to me, "An airship!" And I said, "Mrs. M--- 's chimney is on fire! It looked that near ... To the eye they were little above the housetops.
7. ... a voice from a group of men was heard to say: "Oh, boys, I'll tell you what it is - an aeroplane race."

We have already noted in the Zond IV case that the angular size, a relatively objective estimate, was consistently measured. In this case the description of the noise is remarkably consistent, perhaps because of the ready availability of a charming simile. Here are five consecutive descriptions of the noise:

1. ... a heavy noise like a clap of thunder at a distance;
2. ... a low rumble which at first made me think it was a buggy going along the road from church;
3. ... like thunder, loud at first and rumbling every two or three seconds;
4. ... like a horse and rig going over a bridge;" (5) " ... like a wagon passing over a rough road.

There was more difficulty with conceptions such as angular elevation and distance. As usual, the latter was grossly underestimated.

1. ...midway between the horizon and the sky...
2. ...midway between the earth and the sky...
3. They traveled no faster than a crow flies.
4. ...never have I [seen] so many heavenly bodies moving at one time, or any moving so slowly or in so low an altitude.
5. They looked to pass about one mile south and at an elevation of about 300 feet.
6. ...I saw [it] for about half a minute. In that time it seemed to go about 150 yards.
7. The position in the sky of the first one seemed very low, so low that at first I thought it was a rocket (Skyrockets, of the fireworks type, were a common analogue).

Many more reports could be cited, illustrating comparison with familiar objects (kites, funnels, ships in formation), in some cases misleading, even though the reports taken together present a relatively clear picture. We again can conclude that a substantial number of misleading reports will be introduced in observations of unusual phenomena.