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Popular Science Monthly/Volume 51/June 1897/Globe Lightning

 

GLOBE LIGHTNING.
By M. HAGENAU.

OCCASIONALLY in thunderstorms peculiar electrical apparitions occur, similar in destructiveness to ordinary lightning, but by no means so transient. Their duration is measured, not by thousandths of a second, but by whole seconds or even minutes. They move so slowly that their progress can be accurately followed by the eye. As they generally appear in the form of glowing spheres, they are known as fireballs or globe lightning. The first account of this peculiar form of lightning was given by the celebrated English physicist, Robert Boyle, who described a ball which suddenly appeared on July 24, 1681, on the ship Albemarle. The sailors attacked it in vain with blows and water, but it burned itself out, leaving behind a strong smell of gunpowder.

In Boyle's time ordinary lightning flashes were thought to consist of inflamed gas, so that an occurrence like the above did not appear particularly striking, but later investigators were unable to make the fireball fit their knowledge and theory of electricity, and declared it to be a myth. A layman stated that such a ball appeared in his room during a storm and slowly made its way to the chimney. The scientific people asserted that it was an illusion of the senses, and that there were no such things as fireballs. But the balls continued to appear, in some instances being simultaneously seen by a number of trustworthy witnesses, so that their existence had to be admitted.

Let us notice a few well-attested recent cases:

Dr. A. Wartmann has given the Physical Society of Geneva an account of a ball which he observed during a very violent storm on December 20, 1888, at half past six in the evening, while he was driving from Versoix to Genthod. As he passed the entrance gate of a large mansion he became aware of a very bright and persistent illumination, quite different from the intermittent light of the incessant lightning Hashes.

Thinking it was a fire, he turned and saw, about one thousand feet away, a ball of fire some eighteen inches in diameter. It floated about half its diameter above the ground, and moved parallel with his own course with the swiftness of a hawk, leaving no trace behind it.

At a point about twenty-five yards ahead of him it burst with an appalling crash. "It seemed to me," the report concludes, "to throw out lines of fire. We felt a violent shock, and were blinded for several seconds. As soon as I could distinguish anything, I saw that the horses were standing at right angles to the carriage, with their heads toward the hedge. Their ears drooped, and they exhibited every symptom of intense fright." At the same time, a little less than a mile away, a farmer found himself surrounded by a violet light. He heard a loud explosion, and was thrown bodily ten feet, alighting on a piece of soft turf, more frightened than hurt.

On July 1, 1891, a fireball entered a carpenter's cabin near Schlieben. The carpenter was sitting on the edge of a bed on which a child was sleeping. A ball of fire sprang suddenly and with a loud noise from the fireplace to the bed, which was immediately shattered. Then the ball rolled very slowly to the opposite wall of the room, through which, or the floor, it apparently vanished with another fearful crash without setting fire to anything. The man's wife and another child were sleeping in a second bed and the baby in a cradle, all in the same room, but none of the five persons was wounded or even stunned. All complained of headache and deafness on account of the heavy sulphurous vapor which filled the room, but they soon recovered. Some fractures were discovered about the stove and chimney.

Less fortunate were the children in a schoolhouse in Bouin, France, who were visited by a fireball while at their afternoon prayers. It was preceded by a shower of lime, wood, and stones. The ball, which was small, rolled along under the benches, killing three of the children, and went out through a window pane, in which it merely made a round hole, whereas all the other panes were shattered.

On January 2, 1890, a ball appeared in an electro-technical establishment in Pontevedra, Spain. It was seen to strike the line wires about nine o'clock in the evening under a clear sky, but no one could say just how it struck or from what direction it came. The ball, which was about as big as an orange, moved slowly along the wires to the central station and struck the dynamo, which was running. Before the eyes of the terrified workmen it sprang twice from the dynamo to the wires and back. Then it fell from the machine and burst into a shower of sparks without doing any damage. The electric lamps flickered during its visit, and the thick copper plates of the switch were melted and welded in places.

Of especial interest is the appearance of a large number of balls during a tornado on August 18, 1890, in the French Departement Ille et Vilaine. A farmer of Vizy, who was caught by the storm in the field, saw a fireball fall with great velocity. Panic-stricken, he threw himself on the ground. The luminous ball struck the earth, burst with a loud noise, and covered him with dust.

Dwellers in Vers l'Eau and Samiset saw balls as large as a man's head and of a vivid red, which moved slowly toward some barns, where they vanished after setting the haystacks on fire. In Saint-Claude a great number of balls entered dwellings by the chimneys. They moved slowly to and fro and escaped through windows, doors, and walls, after doing more or less damage. The air in the houses was impregnated with the smell of sulphur or gunpowder.

The region of the Hochgebirge is especially favorable for the observation of globe lightning.

Alluard, the director of the observatory on the Puy-de-Dôme, reports that frequently during thunderstorms showers of small balls of fire are seen falling. On the peak Saentis, in the same region, where a meteorological station was founded at an elevation of twenty-five hundred and four metres in 1882, some very remarkable phenomena were observed by a minister named Studer on June 28, 1885. He and a companion were caught out in the storm after nightfall. All at once they saw on the ridge extending from Saentis to the neighboring peak of Altmann flaring flames and small yellow balls of light. The latter ran along as if on a wire, approached each other, then exploded and fell down. A single larger ball of fire hovered over the same ridge, moving to and fro in a flat parabola with about the speed of a ball thrown by the hand, except that its velocity was uniform. It was visible for several minutes. Then there was a frightful explosion, which seemed to shake the whole mountain to its foundations, and a display of natural fireworks, "of a magnificence never before witnessed," amazed the spectators.

The telephone wire from the station to the valley glowed with great brilliancy as far as it could be seen, and waving sheets of fire extended from it to the ground. Suddenly the whole fiery mass fell to the earth, the wire melted, and the spectators were left in total darkness.

The nature of this peculiar form of lightning is not yet understood, although Planté and F. von Lepel have succeeded in producing in the laboratory, with the aid of powerful electrical machines, small balls of fire which, like those of Nature, moved to and fro for a while and then vanished.

These experiments have suggested the theory that the fireballs consist of heated air and water vapor. But this theory is insufficient, and gives no satisfactory explanation of the various phenomena which have been observed. The subject still needs investigation. It is especially desirable to increase our store of working material—that is, of observations. Whoever, therefore, is fortunate enough to have witnessed a display of globe lightning should communicate his observations to one of the meteorological journals.—Translated for the Popular Science Monthly from Die Gartenlaube, by Lawrence B. Fletcher.