We have among us several minor illusions, which are only less imposing because more familiar; and though often occurring, few are recorded with scientific accuracy. The phosphorescence of the marshes, the ignis fatuus, Will o’Wisp, Jack o’ the Lanthorn, or Friar Rush, and the corpse-candles, are mere luminous exhalations, strained into the marvellous by the vulgar, and thus set down as heralds of mortality. The dancing-light of luminous flies has been termed the _green light of death_; and, if you wish for more, Astrophel, read the “Armorican Magazine” of John Wesley, or the quaint volume of Burton, and thereabouts where he writes in this fashion: “The thickness of the aire may cause such effects, or any object not well discerned in the dark, fear and phantasie will suspect to be a ghost or devil. Glowwormes, firedrakes, meteors, ignis fatuus, which Plinius calls Castor and Pollux, with many such that appear in moorish grounds, about church-yards, moist valleys, or where battles have been fought, the causes of which read in Goclenius, Velcurius, Finkius, &c.” The Parhelia, or mock suns, are produced by the reflection of the sun’s light on a frozen cloud. How readily these phenomena are magnified you may learn from ancient and modern records. In 1223 four suns were seen of crimson, inclosed in a wide circle of crystal colour. This is natural: but then comes the miracle. In the same year two giant dragons were seen in the air, flapping their monstrous wings and engaging in single combat, until they both fell into the sea and were drowned! Then, in 1104, there were seen four white circles rolled around the sun: and in 1688, two suns and a reversed rainbow appeared at Bishop’s Lavington, in Wiltshire: and in February, 1647, there is an account and sketch of three suns, and an inverted rainbow, which Baxter terms “Binorum Pareliorum Φαινομενον.” And because there were two lunar and one solar eclipses in 1652, it was called, as Lily records, “Annus tenebrum,” or “the dark year.” The Corona, or halo around the sun, moon, and stars, is easily illustrated by the zone formed by placing, during a frost, a lighted candle in a cloud of steam or vapour. The Aurora Borealis is _arctic electricity_, and is beautifully imitated by the passage of an electric flash through an exhausted glass cylinder. The rainbow is a combination of _natural prisms_ breaking the light into colours; and it may be seen in the cloud, or in the spray of the ocean, or in the beautiful cascades of Schaffhausen, Niagara, or Terni, or indeed in any foaming spray on which the _meridian_ sunbeams fall, or even in the dewy grass, lying, as it were, on the ground.