To similar causes as those now alluded to are to be attributed such phenomena as the following:
The Spectre of the Brocken. This is a wonderful and, at first sight, a terrific phenomenon, which is sometimes seen from the summit of one of the Hartz mountains in Hanover, which is about 3,300 feet above the level of the sea, and overlooks all the country fifteen miles round. From this mountain the most gigantic and terrific spectres have been seen, which have terrified the credulous, and gratified the curious, in a very high degree. M. Hawé who witnessed this phenomenon, says, the sun rose about four o’clock, after he had ascended to the summit, in a serene sky, free of clouds; and about a quarter past five, when looking round to see if the sky continued clear, he suddenly beheld at a little distance, a human figure of a monstrous size turned towards him, and glaring at him. While gazing on this gigantic spectre, with a mixture of awe and apprehension, a sudden gust of wind nearly carried off his hat, and he clapt his hand to his head to detain it, when to his great delight, the colossal spectre did the same. He changed his body into a variety of attitudes,all which the spectre exactly imitated, and then suddenly vanished without any apparent cause, and, in a short time as suddenly appeared. Being joined by another spectator, after the first visions had disappeared, they kept steadily looking for the aërial spectres, when two gigantic monsters suddenly appeared. These spectres had been long considered as preternatural, by the inhabitants of the adjacent districts, and the whole country had been filled with awe and terror. Some of the lakes of Ireland are found to be susceptible of producing illusions, particularly the lake of Killarney. This romantic sheet of water is bounded on one side, by a semicircle of rugged mountains, and on the other by a flat morass; and the vapours generated in the marsh, and broken by the mountains, continually represent the most fantastic objects. Frequently men riding along the shore are seen as if they were moving across the lake, which is supposed to have given rise to the legend of O’Donougho, a magician who is said to be visible on the lake every May morning.
There can be little doubt that most of those visionary appearances which have been frequently seen in the sky and in mountainous regions, are phantoms produced by the cause to which I am adverting, such as armies of footmen and horsemen, which some have asserted to have been seen in the air near the horizon. A well authenticated instance of this kind occurred in the Highlands of Scotland:—Mr. Wren of Wetton Hall, and D. Stricket his servant, in the year 1744, were sitting at the door of the house in a summer evening, when they were surprised to see opposite to them on the side of Sonterfell hill—a place so extremely steep, that scarce a horse could walk slowly along it—the figure of a man with a dog pursuing several horses, all running at a most rapid pace. Onwards they passed till at last they disappeared at the lower end of the Fell. In expectation of finding the man dashed to pieces by so tremendous a fall, they went early next morning and made a search, but no trace of man or horse, or the prints of their feet on the turf could be found. Sometime afterwards, about seven in the evening, on the same spot, they beheld a troop of horsemen advancing in close ranks and at a brisk pace. The inmates of every cottage for a mile round beheld the wondrous scene, though they had formerly ridiculed the story told by Mr. Wren and his servant, and were struck with surprise and fear. The figures were seen for upwards of two hours, till the approach of darkness rendered them invisible. The various evolutions and changes through which the troops passed were distinctly visible, and were marked by all the observers. It is not improbable that these aërial troopers were produced by the same cause which made the castle of Dover to appear on the side of the hill next to Ramsgate, and it is supposed that they were the images of a body of rebels, on the other side of the hill, exercising themselves previous to the rebellion in 1745.[12]
I shall mention only another instance of this description which lately occurred in France, and for a time caused a powerful sensation among all ranks. On Sunday the 17th of December, 1826, the clergy in the parish of Migné, in the vicinity of Poictiers, were engaged in the exercises of the Jubilee which preceded the festival of Christmas, and a number of persons to the amount of 3000 souls assisted in the service. They had planted as part of the ceremony, a large cross, twenty-five feet high, and painted red, in the open air beside the church. While one of the preachers, about five in the evening, was addressing the multitude, he reminded them of the miraculous cross which appeared in the sky to Constantine and his army, and the effect it produced—when suddenly a similar celestial cross appeared in the heavens just before the porch of the church about 200 feet above the horizon, and 140 feet in length, and its breadth from three to four feet, of a bright silver colour tinged with red. The curate and congregation fixed their wondering gaze upon this extraordinary phenomenon, and the effect produced on the minds of the assembly was strong and solemn: they spontaneously threw themselves on their knees; and many, who had been remiss in their religious duties, humbly confessed their sins, and made vows of penance and reformation. A commission was appointed to investigate the truth of this extraordinary appearance, and a memorial stating the above and other facts was subscribed by more than forty persons of rank and intelligence, so that no doubt was entertained as to the reality of the phenomenon. By many it was considered as strictly miraculous, as having happened at the time and in the circumstances mentioned. But it is evident, from what we have already stated, that it may be accounted for on physical principles. The large cross of wood painted red was doubtless the real object which produced the magnified image. The state of the atmosphere, according to the descriptions given in the memorial, must have been favourable for the production of such images. The spectrum of the wooden cross must have been cast on the concave surface of some atmospheric mirror, and so reflected back to the eyes of the spectators, from an opposite place—retaining exactly the same shape and proportions, but dilated in size; and what is worthy of attention, it was tinged with red, the very colour of the object of which it was the reflected image.
Such phenomena as we have now described, and the causes of them which science is able to unfold, are worthy of consideration, in order to divest the mind of superstitious terrors, and enable it clearly to perceive the laws by which the Almighty directs the movements of the material system. When any appearance in nature, exactly the reverse of every thing we could have previously conceived—presents itself to view, and when we know of no material cause by which it could be produced, the mind must feel a certain degree of awe and terror, and will naturally resort to supernatural agency as acting either in opposition to the established laws of the universe, or beyond the range to which they are confined. Besides the fears and apprehensions to which such erroneous conceptions give rise, they tend to convey false and distorted impressions of the attributes of the Deity and of his moral government. Science, therefore, performs an invaluable service to man, by removing the cause of superstitious alarms, by investigating the laws and principles which operate in the physical system, and by assigning reasons for those occasional phenomena, which at first sight appeared beyond the range of the operation of natural causes.
The late ingenious Dr. Wollaston illustrated the causes of some of the phenomena we have described, in the following manner. He looked along the side of a red hot poker at a word or object ten or twelve feet distant; and at a distance less than three eights of an inch from the line of the poker, an inverted image was seen, and within and without that image, an erect image, in consequence of the change produced, by the heat of the poker, in the density of the air. He also suggested the following experiment as another illustration of the same principle, namely, viewing an object through a stratum of spirit of wine lying above water, or a stratum of water laid above one of syrup. He poured into a square phial a small quantity of clear syrup, and above this he poured an equal quantity of water which gradually combined with the syrup, as seen at A. fig. 30. The word ‘Syrup,’ on a card held behind the bottle, appeared erect when seen through the pure spirit, but inverted, when seen through the mixture of water and syrup. He afterwards put nearly the same quantity of rectified spirits of wine above the water, as seen at B, and he saw the appearance as represented, namely, the true place of the word ‘Spirit,’ and the inverted and erect images below. These substances, by their gradual incorporation, produce refracting power, diminishing from the spirit of wine to the water, or from the syrup to the water; so that by looking through the mixed stratum, an inverted image of any object is seen behind the bottle. These experiments show that the mirage and several other atmospherical phenomena may be produced by variations in the refractive power of different strata of the atmosphere.
figure 30.
It is not unlikely that phenomena of a new and different description from any we have hitherto observed, may be produced from the same causes to which we have adverted. A certain optical writer remarks—‘If the variation of the refractive power of the air takes place in a horizontal line perpendicular to the line of vision, that is, from right to left, then we may have a lateral Mirage, that is, an image of a ship may be seen on the right or left hand of the real ship, or on both, if the variation of refractive power is the same on each side of the line of vision, and a fact of this kind was once observed on the Lake of Geneva. If there should happen at the same time, both a vertical and a lateral variation of refractive power in the air, and if the variation should be such as to expand or elongate the object in both directions, then the object would be magnified as if seen through a telescope, and might be seen and recognized at a distance at which it would not otherwise have been visible. If the refracting power, on the contrary, varied, so as to construct the object in both directions, the image of it would be diminished as if seen through a concave lens.’