MIRACLE PLAY 



3840 



MIRAGE 



and the fourth, at the time when Jesus was on 

 earth. They were unusual events, such as the 

 dividing of the waters in the Jordan to allow 

 the Children of Israel to cross, or the feeding 

 of the five thousand with five loaves and two 

 fishes, and all were intended to show divine 

 authority. Thus people were often reassured. 

 or aided in their faltering faith in God, and 

 thus miracles helped in establishing the king- 

 dom of God on earth. 



MIRACLE PLAY, a religious play or drama 

 founded on subjects taken from lives of the 

 saints or from Scripture narratives which were 

 popular in England during the Middle Ages. 

 These dramas were shown to the people at cer- 

 tain times of the year and reached their height 

 of popularity in the thirteenth century, during 

 the time of Chaucer. The institution of Corpus 

 Christi Day, with its elaborate ceremonies and 

 processions, gave a great impetus to these 

 plays. They passed into the hands of trades- 

 men's associations or guilds after leaving the 

 churches, as by Papal edict clerics, or those 

 under holy orders, were forbidden to appear on 

 the stage. The plays continued to be given 

 until the reign of Elizabeth, when they ceased 

 to have vital interest, but their influence was 

 great in preparing the way for a more modern 

 drama. Very few texts of these miracle plays 

 have been preserved, but in structure and aim 

 they were similar to the mystery plays (which 

 see). 



MIRAGE, merahzh'. During the first inva- 

 sion of Egypt by the army of Napoleon, in 

 1789, the soldiers were frequently annoyed by 

 deceptive appearance of cool lakes across the 

 shimmering expanse of heated desert air. One 

 of the members of the expedition, a French 

 mathematician named Gaspard Monge, gave 

 what is supposed to be the first scientific ex- 

 planation of this phenomenon, to which the 

 name mirage, from the Latin word mirari, 

 meaning to wonder, has been aptly applied. 



It often happens in deserts that the air near 

 the surface of the sand becomes abnormally 

 heated, so there is a well-defined bounding sur- 

 face between the lower strata and the cooler, 

 denser layers of air above; this bounding sur- 

 face acts like a reflecting mirror, in which ob- 

 jects appear inverted. A cloud or portion of 

 sky, for instance, may be so reflected by this 

 natural mirror that it will look exactly like 

 a body of water lying on the sands of the des- 

 ert. Since the reflecting surface often varies 

 in position, owing to the constant addition of 

 heat waves to the upper strata of air, the re- 



flected cloud or bit of sky will seem to be a 

 lake whose waters are being stirred by the wind. 

 A common type of mirage is that in which 

 trees are seen in an inverted position, as if 

 reflected in a body of water. The ray from a 

 tree top coming obliquely downward may be 

 so bent from its 

 first direction as 

 it passes through 

 the different lay- 

 ers of air that it 



is sent obliquely 

 upward to the 

 eye, but the eye 

 follows the ray 

 back in a straight MIRAGE IN THE DESERT 

 line. The low, Let it be supposed that the 

 i__i + . t air strata decrease in den- 



hot stratum of sity from to d . a ray of 



air sprvp? a<? a light coming from an object 

 aS a (the tree) will be refracted 

 reflecting mirror, in passing downward through 

 . ,, , the stratum a, still more in 



and the observer passing through b, and so on 

 imae-inps hp ?PPS until it penetrates a stratum 

 S which may be d, where the 

 in the distance a ray is totally reflected. The 

 direction of the ray will then 

 green oasis. be upward, but will be re- 



Mi rap-ps arp fracted toward the perpen- 

 dicular as it passes through 



also observed at strata of increasing density, 

 , , . ... so when the ray reaches the 

 sea, but in this eye the object will appear in 

 case the denser the direction of e. 

 layers of air are next to the surface of the 

 water, and the reflected object seems to be 

 suspended in the sky and inverted. The ac- 

 companying drawings show the direction taken 

 by rays of light passing through layers of air of 



MIRAGE OVER THE WATER 

 Air is denser near the surface of the water 

 than it is at higher altitudes, because the water 

 cools it. The course of the rays is shown in the 

 illustration. A vessel so far distant as to be hid- 

 den by the curvature of the earth will appear 

 above the horizon when the rays of light are at 

 first refracted from the perpendicular until the 

 lighter stratum is reached at d, when total reflec- 

 tion takes place. By this the ray is given an 

 inclination downward, so the object appears in 

 the direction of e. 



different densities, producing in one case mirage 

 of the desert, and in the other mirage of the 

 sea. 



The Fata Morgana (fah'tah mawrgah'nah) 

 is a form of complicated mirage occasionally 

 observed in the Strait of Messina. It was so 



