St. Elmo's Fire is an electrical discharge observed around masts, poles, and spires causing ionisation of the surrounding atmosphere. It often produces crackling noises as well as giving rise to luminous displays often described as fireworks, jets, stars, corona, streams, or sparking. St. Elmo's Fire can cause radio disturbances, but is often taken to be a good sign, because it occurs at the end of thunderstorms, hence signifying clearer weather to come. As St. Elmo is the patron saint of sailors, the sailors took it to be a sign of St. Elmo appearing to them, and gave it its common name.
The coronal discharge is often refered to as the corposant—from the Old Spanish corpo santo, i.e. holy, or saint's, body—the oldest reference for which in the OED is Eden's Arte of Nauigation (1561), where he speaks of "[s]hining exhalations that appeare in tempestes: whiche the Mariners call sant~elmo or Corpus sancti".
The Greeks yclept St. Elmo's Fire Helena, and the rarer double jet forms Castor and Pollux after the two brightest stars in Gemini: not suprising that the phenomenon would be named after stars of high marine nagivational signifigance. Many famous sailors and explorers, including Chistopher Columbus and Charles Darwin, are noted to have observed the phenomenon. St. Elmo's Fire has also been mentioned in the works of Julius Caesar, Pliny, Melville, and even Shakespare, who wrote the following lines of it in The Tempest, I.ii.196-201:
ARIEL I boarded the king's ship; now on the beak, Now in the waist, the deck, in every cabin, I flamed amazement: sometime I'd divide, And burn in many places; on the topmast, The yards and bowsprit, would I flame distinctly, Then meet and join.
Other references: Hazlitt's edition of Brand's Antiquities (1905) under "Castor and Pollux" (via the 1911 Encyclopaedia), A Goodly Gallerye (Book of Meteors), by William Fulke. @@ More photos of St. Elmo's Fire.
Excerpt from The Nautical Magazine (1832), p.696 onward.
Saint Elmo's Fire.
Among the many natural phenomena which have excited the superstitious awe of mankind in past ages, but which happily have met with their explanation among the generalizations of modern science, are those remarkable luminous appearances which in certain states of the air invest pointed bodies, such as the masts of ships, and are known to the English sailors as Comazants,—to the French and Spaniards under the more poetican name of St. Elmo's (or St. Helmo's) Fires,—and to the Iralians as the Fires of St. Peter and St. Nicholas; the Portuguese call them Corpo Santo, and in some parts of the Mediterranean they are named after St. Clair.
One of the most ancient notices of this phenomenon is recorded in the Commentaries of Cæsar, in his book "De Bello Africano," where it is spoken of as a very extraordinary appearance.—"In the month of February, about the second watch of the night, there suddenly arose a thick cloud, followed by a shower of hail, and the same night the points of the spears belonging to the fifth legion seemed to take fire." Seneca also, in his "Quæstiones Naturales," states that a star settled on the lance of Gylippus as he was sailing to Syracuse. Pliny, in his second book of Natural History, calls these appearances stars, and says that they settled not only upon the masts and other parts of the ships, but also upon men's heads.—"Stars make their appearance both at land and sea. I have seen a light in that form on the spears of soldiers keeping watch by night upon the ramparts. They are seen also on the sail-yards, and other parts of ships, making an audible sound, and frequently changing their places. Two of these lights forbode good weather and a prosperous voyage, and extinguish one that appears single and with a threatening aspect,—this the sailors call Helen, but the two they call Castor and Pollux, and invoke them as gods. These lights do sometimes, about evening, rest on men's heads and are a great and good omen. But these are among the awful mysteries in nature." Livy also (c. 32.) relates that the spears of some soldiers in Sicily, and a walking stick which a horseman in Sardinia held in his hand, seemed to be on fire. He states also; that the shores were luminous with frequent fires. Plutrach also records the fact, and Procossius affirms that, in the war against the Vandals, the Gods favoured Belisarius with the same good omen.
There is no doubt that during many centuries these appearances continued to be regarded with mingled feelings of admiration and fear. In the record of the second voyage of Columbus (Historia del Almirante, written by his son) is a passage which will illustrates the superstituon of the fifteenth century. "During the night of Saturday (October 1493), the thunder and rain being very violent, St. Elmo appeared on the top-gallant mast with seven lighted tapers; that is to say, we saw those fires which the sailors believe to proceed from the body of the saint. Immediately all on board began to sing litanies and thanksgivings, for the sailors hold it for certain, that as soon as St. Elmo appears, the danger of the tempest is over." Herrera also notices that Magellan's sailors had the same superstitions.
Thus it appears that the auspicious view which the ancients took of this phenomenon continues, also during the middle ages, modified, however, by the religious faith of the observed. As we approach our own times supersititon gradually relinquishes its hold of this appearance; and mere matter-of-fact observers, forgetful of the bodies of saints illuminated by wax tapers, speak of it as it is, and even make it ridiculous by attributing to it a material character which it certainly does not possess Forbid, sailing among the Balearic islands in 1896, relates that during the night a sudden darkness came on, accompanied by fearful lightning and thunder. All the sails were firled, and preparations were made for the storm: "We saw more than thirty St. Elmo's fires. There was one playing upon the vane of the main mast more than a foot and a half high. I sent a man up to bring it down. When he was aloft he cried out that it made a noise like wetted gunpowder in burning. I told him to take off the vane and come down; but scarcely had he removed it from its place than the fire quitted it and re-appeared at the end of the mast, without any possibility of removing it. It remained for a long time and gradually went out."
We come now to divest the phenomenon of all its romance in the plain statements of two intelligent observers. The first is Lieut. Milne of the Royal navy, who, in a communication to Professor Jamieson states that he was off the Coast of Brazil in September 1827; the day had been sultry, and heavily charged clouds had been collecting in the south-west. As evening approached it became very dark; the lightning was very vivid, and was followed by heavy peals of distant thunder. About ten o'clock a light was observed on the extremity of the vane staff at the masthead, and shortly afterwards another on the weather side of the fore-top-sail-yard.
One of the midshipmen, curious to examine this appearance a little more closely went aloft. He found that it appeared to proceed from an iron bolt in the yard-arm; its size was rather larger than that of a walnut, and it had a faint yellow cast in the centre, approaching to blue on the external edge. On applying his hand to it it made a noise like the burning of a port-fire, emitting at the same time a dense smoke without any sensible smell.
On taking away his hand it resumed its former appearance, but he applied the sleeve of his wet jacket, it ran up it, and immediately became extinguished, and did not appear again. The light onthe vane-staff retained its position for upwards of an hour, but on account of the heavy rain, and probably also from having been struck by the vane attached to the staff, it went out, but resumed its position after the rain had ceased, although with a less degree of brightness.
In the above account the only circumstance which we do not understand is the dense smoke said to have been emitted by the light. This may perhaps be attributed to the imagination of the observers, who witnessed the phenomenon for the first time. Other accouts are given by Lieutenant Milne, but these we need not repeat; he says, that the fire usually appeared on metal, such as iron bolts and copper spindles; but on one occasion he noticed it on a spindle of hard wood, from which the copper had been removed. He states that bad weather always followed the phenomenon.
In a letter from Mr. William Traill, of Kirkwall, to Professor Traill, dated 16th of May, 1837, and published in the scientific journals of the time as an interesting notice of St. Elmo's Fire in Orkney. During a tremendous gale in Feburary, 1837, a large boat was sunk, but the crew succeeded in getting her to the shore. This was accomlished by night; they had to wait until three o'clock ont he following morning until the tide should ebb from her. During this time she was attached to the shore by an iron chain about thirty fathoms long, which did not touch the water, when suddenly Mr. Traill beheld "a sheet of blood-red flame extending along the shore, for about thirty fathoms broad and one hundred fathoms long, commencing at the chain and stretching along in the direction of the shore, which was E.S.E., the wind being N.N.W. at the time. The flame remained about ten seconds, and occured four times in about two minutes." The boatmen, about thirty in number, who were sheltering themselves from the weather, were apparently alarmed, and about to make enquiries, when atention was suddenly attracted by a most splendid appearance of the boat. "The whole mast was illuminated, and from the iron spike at the summit a flame of one foot long was pointed to the N.N.W., from which a thunder-cloud was rapidly coming. The cloud approached, which was accompanied by thunder and hail; the flame increased and followed the course of the cloud till it was immediately above, when it arrived at the length of nearly three feet, after which it rapidly diminished, still pointing to the cloud as it was borne rapidly on to S.S.E. The whole lasted about four minutes and had a most splendid appearance."
The popular opinion is that St. Elmo's Fire now appears only on the points of ships' masts; but M. Arago confutes this opinion by adducing a variety of cases, which seem to prove that the only reason why the phenomenon is not commonly seen on the tops of church spires, and on the summits of high buildings in general, is simply because people never look out for it. But a few recorded instances are sufficient to prove that good observers only are wanting to make the phenomenon much more common.
M. Binon, who was cure/ of Rouzet during twenty-seven years, informed Mr. Watson, the electrician, that during great storms, accompanied with black clouds and frequent lightnings, the three pointed extremeties of the cross of the steeple of that place appeared surrounded with a body of flame, and that when this phenomenon has been seen the storm was no longer to be dreaded, and calm weather returned soon after. In August, 1768, Lichtenberg noticed the St. Elmo's Fire on the steeple of St. Jacques at Gottingen. In January, 1778, during a violent storm, accompanied by rain and hail, M. Mongery noticed luminous tufts on many of the most elevated summits of the city of Rouen.
The observations of Cæsar, respecting the luminous points of his soldiers' spears, has been repeated in modern times, and still more remarkable cases have occured. In Januard, 1822, during a heavy fall of snow, M. de Thielaw, while on the road to Frey Viry, noticed that the extremeties of the brances of all the trees by the road side were luminous, the light appearing of a faint bluish tinge. In January, 1824, after a storm, M. Masadorf noticed in a field near Cothen, a cart-load of straw situated immediately under a large black cloud; the extremeties of the straw appeared to be on fire and the carter's whip was also luminous. This phenomenon lasted about ten minutes, and disappeared as the black cloud was blown away by the wind. Rozet, in his work on Algiers, relates, that on the 8th of May, 1831, after sunset, some artillery officers were walking during a storm on the terrace of the fort Babazoun at Algiers; their heads being uncovered, they saw, to their great astonishment, that each one's hair stood on end, and that each hair was terminated by a minute luminous tuft; on raising the hands, these tufts formed also at the extremeties of their fingers.
All these and various other phases, under which the St. Elmo's Fire appears, admit of explanation on the principle which regulates a thunder storm. The electrical balance between the clouds, a portion of the earth's surface directly opposed to these clouds, and the intermediate air being disturbed, the particles of air, by a process called induction, increase this disturbance, throwing the clouds and the earth into two highly excited opposite states, which tend more and more to combine, according to the length of the process, until at last a union is effected by what Dr. Faraday calls a disruptive discharge, which is usually accompanied by lightning and thunder.
If it were possible to connect the clouds and the eath by a good metallic conductor, the electrical balance would be restored, and no such violent discharge would ensue. But it sometimes happen that when the air is in a highly excited state, a point projecting into it will effect a partial discharge. This is accompanied by a luminous burst of light and a sort of roaring noise. The experiment can be shown at the electrical machine, and is known as the brush discharge. It usually takes place betwen a good and a bad conductor; it commences at the root of the brush and is complete at the point of the rod before the more distant particles of air acquire the same electrical intensity.
Hence, in the foregoing examples, it will be seen that the points of ships' masts, the extremeties of church steeples, and even less elevated objects, are all subject to a visitation from St. Elmo's Fire; or in other words, when placed in highly excited air and electrical discharge may take place upon them, of so slow a character as to be entirely free from danger. It is the immense velocity with which lightning travels, which causes it to commit such fearful havoc when it strikes badly conducted substances.
Excerpt from Elements of Meteorology, by John Brocklesby (1851); pp.156-7.
382. St. Elmo's Fire. When in a darkened room a needle is brought near to the charged conductor of an electrical machine, the point is tipped with a vivid light, caused by the flow of electricity from the conductor to the needle. In the same manner when thunder-clouds approach very near the earth, lightning does not always occur; but the electricity becomes so intense, that it escaped from one to the other by points upon the surface of the earth, which then glow with a brilliant flame. This phenomenon has received the appellation of St. Elmo's fire. It was known to the ancients by the name of Castor and Pollux, and many instances have been recorded by classic writers. On the night before the battle that Posthumius gained over the Sabines, the Roman javelins emitted a light like torches; and Cæsar relates that during the African war, in the month of February, there suddenly arose, about the second watch of the night, a dreadful storm that threw the Roman army into great confusion, at which time the points of the darts of the fifth legion appeared to be on fire.
383. The fire of St. Elmo is often finely displayed upon the masts of vessels. An extraordinary instance, which happened in 1696, is thus related by Count Forbin: "In the night it became extremely dark, and thundered and lightened fearfully. We saw upon different parts of the ship about thirty St. Elmo's fires; among the rest was one upon the top of the vane of the mainmast, about eighteen inches long. I ordered one of the sailors to take the vane down, but he had scarcely removed it when the fire again appeared upon the top of the mast, where it remained for a long time, and then gradually vanished." When Lord Napier was on the Mediterranean, in June, 1818, he observed, during a dark and stormy night, a blaze of pale light upon the mainmast of his vessel. It appeared near the summit, and extended about three feet downward, flitting and creeping around the surface of the mast. The heads of the other two masts presented a similar appearance. At the end of half an hour, the flames were no longer visible.
384. This phenomenon frequently occurs on the summits of mountains, when thunder clouds pass near them. Saussure observed it upon the Alps, in 1767. On extending his arm, he experienced slight electric shocks, accompanied by a whistling sound, and obtained distinct sparks from the gold button of a hat belonging to one of his party. It is often noticed at Edinburg castle, which stands upon a high rock, 250 feet above the surrounding country. Upon the approach of a storm, the bayonets of the soldiers mounting guard are frequently seen capped with flame, and an iron ramrod, placed upright upon the walls, presents a like appearance.
A singular instance of spontaneous electricity took place at Algiers, on the 8th of May, 1831. During the evening of this day, as some French officers were walking with their heads uncovered, each was surprised at seeing the hairs upon the heads of his companions erect, and tipped with flame. Upon raising their hands, they perceived a similar light flitting upon the ends of their fingers.
A remarkable case of this kind was observed by Pres. Totten, of Trinity College, at Hartford, Ct., in the month of Dec. 1839. As this gentleman was walking one evening in the midst of a heavy snow-storm, protected by an umbrella, his attention was arrested by momentary flashes of light, which at intervals illumined his path. The source of the light was detected upon meeting another person, the point of whose umbrella was seen covered with flame, which was constantly escaping in flashes. The light first noticed by Pres. Totten, proceeded from his own umbrella.
Excerpt from John Lee Comstock (1837), A Treatise on Mathematical and Physical Geography; pp.275-6.
Fire of St. Elmo.
This light was formerly supposed by mariners, to be a visible representation of a spirit they called St. Elmo, and who was the titelar saint of those who traverse the mighty deep; and hence its name.
St. Elmo's Fire is a luminous meteor that frequently appears to settle on the mast-head of vessels, in warm weather, and especially in hot climates, and is considered an electrical phenomenon, though is is never known to produce any of the disastrous effects of lightning. When it is confined to the topmast, it is considered a prognostic of bad weather, though not in such a degree as to do injury. But when it descends down the mast, it is believed a sure proof that a storm is coming, which will be, more or less disastrous, in proportion to the distance it descends.
Falconer, in his Shipwreck, alludes to this, when he says—
"High on the mast, with pale, and livid rays,
Amid the gloom, portentous meteors blaze."
This appearance is explained by the known aptitude of pointed conductors to transfer the electricity of the atmosphere, in silence, or without a shock, and hence the reason why sharp points are made to terminate lightning rods.
It is possible that the light of St. Elmo, may be connected with a change of the weather, since the electrical state of the atmosphere is undoubtedly concerned in the production of clouds and storms, as well as in that of lightning and thunder. It would not, therefore, be unphilosophical to consider, with the sailors, that these appearances prognosticate such changes.
Humboldt, during one of his voyages, observed this phenomenon, and thus describes it; "On observing the appearance of the masts, the main-top-gallant-mast-head, from the truck, to three feet down, was perfectly enveloped in a cold blaze of pale phosphorus-looking light, completely embracing the circumference of the mast, and attended with a flitting, or creeping motion, as exemplified experimentally, by the application of common phosphorus upon a board. The fore, and mizzen-top-gallant-mast heads, exhibited a similar appearance. This curious illumination continued with undiminished intensity, for eight, or ten minutes, when becoming gradually fainter, and less extensive, it finally disappeared, after a duration of not less than half an hour."
From the same cause, arose the phenomenon observed by M. Allamond, who, having closed his umbrella during a thunder storm, lest the electricity should be attracted by its metallic point, saw that the brim of his hat was surrounded by a broad band of light, which became more intense, as he passed his hand over it. This appearance vanished as soon as he came near to some tall tress, which probably conducted the electricity to the ground, from the highly excited atmosphere.
On p.100 of Julian Jackson's What to Observe (1841), Jackson refers to St. Elmo's Fire as Cuerpo Santo and Corpusance, and says that they are "presumed to be purely electrical". He says that it's always seen as a precursor to storms.