Explications proposées

Many explanations of the Brown Mountain lights have been offered. The principal ones that have come to the notice of the writer are briefly outlined below.

1. 1. Will-o'-the-wisp: A light called will-o'-the-wisp is sometimes seen over marshy places and is supposed to be due to the spontaneous combustion of marsh gas. There are, hcwever, no marshy places on or about Brown Mountain, and the lights seen by the writer could not be ascribed to such a cause.
2. Phosphorus: It has been suggested that the lights may be caused in some way by the element phosphorus. Phosphorus, however, is so easily oxidized that it does not occur in the free state. It is usually locked up in stable and relatively insoluble chemical compounds and therefore cannot be a cause of the Brown Mountain light.
3. Phosphorescence (fox fire): Some organic bodies, such as stumps or logs, become luminous or phosphorescent by slow oxidation and combustion in the course of their decay. Such lights are too feeble to be seen at a distance of several miles and are unlike the lights seen by the writer.
4. Radium emanations: The late F. H. Hossfield is reported to have found a piece of pitchblende, an ore of radiumt near the southwest end of Brown Mountain, and some therefore think that Brown Mountain may contain a large body of radium ore, which might by emanation produce the observed lights. So far as the writer has been able to learn, the material that was supposed to be pitchblende was never so identified by actual tests, and the place where it was found is not accurately known. The specimen itself has been lost; but pitchblende, even if it occurred ---in large clepostts, could not give rise to lights like those seen over Brown Mountain. No known radium ore shows that kind of luminosity.
5. Chemical reaction between hydrogen sulfide a~d lead oxide: In a letter received from Mr. E. C. Ivey, of Hickory, it is suggested that the lights may be so caused, and it is stated that both hydrogen sulfide and lead oxide occur in Brown Mountain and that hydrogen sulfide will ignite in the presence of lead oxide. Sulphur springs occur on the west side of Brown Mountain and lead prospects are reported on the east side, but the possibility that there is any direct relation between them is so slight as to be highly improbable.
6. "Blockade" (illicit) stills: Many stills have been operated by"moonshiners" in the vicinity of Brown Mountain. A man who claims to have been an eyewitness states that screens are placed about these stills to shut off the light from the fires but that from time to time the fires are raked out and the covers of the stills removed, so that the clouds of steam whjch arise from them are illuminated by the fires below. The "moonshiners" are also said to use lights for signaling. It is possible that the light with "seething motion" seen by Mr. Gregory may have been of this origin, but there are not enough such stills and they probably would not be in sufficiently continuous operation to produce lights in the number and in the regularity of appearance of those seen at Brown Mountain.
7. St. Elmo's fire: St. Elmo's fire is a brushlike, luminous, electrical discharge that sometimes takes place £rem masts, lightning conductors, and other pointed objects, especially during thunderstorms. In his correspondence with Messrs. Clark and Perry, the trustworthy observers already mentioned, Dr. C. G. Abbot, of the Smithsonian Institution, suggested that the Brown Mountain light may be due to St. Elmo's fire, but there seems to be little in common between the lights seen by the writer and St. Elmo's fire as usually described. In a second letter to Dr. Abbot, dated January 9, 1920, Professor Perry states the case clearly when he says, "My own impression of St. Elmo's fire and similar phenomena was that it occurred at the extremity of some solid conductor instead of occurring, as in the case of the Brown Mountain lights, in the air, at a great distance from any object."
8. Andes light: The name "Andes light," according to information furnished to the writer by Dr. Herbert Lyman, of the U.S. Weather Bureau, is given to a very striking luminous discharge of electricity seen over the crest of the Andes in Chile, where ordinary thunderstorms are almost unknown. The mountain peaks appear to act as gigantic lightning rods, between which and the clouds silent discharges take place on a vast scale.
   The principal writer on the Andes light is Dr. Walter Knoche, who was for several years director of the Central Meteorological and Geophysical Institute at Santiago, Chile, and who says that he has seen this light at distances greater than 300 miles. Most of the discharges appear to produce glimmering lights that have circular borders. The flashes are bright at their starting points but diminish rapidly in intensity and then slowly disappear. The area of this silent discharge is at first small and lies over the main cordillera. but it soon extends far over the zenith and sometimes reaches over the coast cordillera and out to sea. The phenomena is best seen in a clear sky.
   Dr. Guy Hinsdale, in the Scientific Monthly for September 1919, reports that in western Virginia, where there are "numerous parallel ridges with intervening deep and narrow valleys, it occasionally happens that an electric discharge takes place from the summits of these ridges into the atmosphere. There is nothing audible, but merely the sudden glow of the higher clouds in the dark, night."
   The appearance of the Andes light, as shown in illustrations given by Dr. Knoche and in the accounts of it already cited, is totally different from that of the Brown Mountain light as seen by the writer during his investigation or as described by others, and there appear to be no geologic conditions at or near Brown Mountain that would produce electrical discharges there rather than at Blowing Rock or Grandfather Mountain or any other prominent point in this region.
9. Mirage: Mr. H. C. Martin, in the Lenoir Topic for April 19, 1916, and afterward in conversation with the writer, has suggested that the lights may be due to mirage. He thinks that air currents of different temperature and density may produce between them reflecting surfaces, from which bright stars or other lights might be reflected in such a way as to produce the effects commonly seen. According to this explanation the wavering of the reflecting surface would cause the sudden appearance, wavering, and disappearance of the light.
   A mirage is a phenomenon of the daytime rather than of the nignt. The requisite conditions are that the air must be still and that the lower layers, heated by radiation from the underlying surface, must become less dense than the overlying layers and yet be unable to escape. With the least disturbance of these unstable conditions the overheated air suddenly "spills" upward and mirage disappears. The conditions in a mountain gorge such as that of Wilson Creek east of Brown Mountain are entirely unfavorable to mirage, for as soon as the lower air becomes warmed it may escape up the surface slopes, and at evening there is likely to be a downward draft of cool air from the neighboring uplands. Yet Mr. Martin, in seeking in air currents of different temperature and density an explanation of the light, has hit upon what the writer believes to be a fundamental element in the problem, as will be more fully explained below.
10. Locomotive headlights: D. B. Sterrett, of the U.S. Geological Survey, who investigated the light on October 11, 1913, noted that the headlights of westbound Southern Railway locomotives could be observed from Brown Mountain and that they were brilliant enough to be seen in the same straight line from Loven's place, 6 miles beyond. He checked on the train schedules and concluded that locomotive headlights were "beyond doubt" the cause of the Brown Mountain light. Objection to this view has been raised on the ground that a locomotive headlight casts a beam) which, like that of a searchlight as frequently seen, can be readily identified. This objection is considered under the heading clear sky. "Conclusions."
11. Automobile headlights: Powerful headlights on automobiles have been suggested as a source of the Brown Mountain light. The objection made to this suggestion is similar to that made to the suggestion that they are caused by locomotive headlights, and it fails for the same reasons. When seen at long distances the two kinds of headlights behave in a similar manner. Of the 23 lights recorded by instrumental observation in the investigation here reported, ll were probably automobile headlights.