MIRAGE. 



567 



thus proving that the sun and the shadow are 

 moving about the mill as a pivotal center. 

 The reversed image of the mill in this case 

 does not appear in the air, because the south- 

 ern motion of the rising sun causes the shadow 

 to fall upon the beach westward of it, and 

 therefore it is not reflected as it would be if it 

 were projected on to the water. 



Illustration No. 2 shows the shadow projected 

 horizontally, the sun being just above the hori- 

 zon. In this illustration, No. 3, the feathered 

 end of the broken arrow shows the direction 

 whence the light is proceeding, the sun hav- 

 ing now ascended to that angle above the hori- 

 zon. The point where the arrow breaks indi- 

 cates the sunlight impinging upon the surface 

 of the water, and being thence reflected up- 

 ward and carrying with it the shadow of the 

 mill, which must necessarily ascend as the sun 

 does. 



In the fourth illustration we have a still 

 more complete example of specters in the air, 



so located as to intercept the lower part of the 

 shadow only, and the shadow of the "top- 

 hamper" passes over it, and when intercepted 

 by some other cloud becomes visible also. 

 For these reasons and others, "the phantom 

 ship" or "Flying Dutchman" sometimes in- 

 spired terror by mysteriously going to pieces, 

 and at others disappearing by sinking into the 

 ocean, or appearing by ascending from it ; and 

 the mystery was deepened by some of the top- 

 sails only appearing above the sea at times and 

 then sinking back into it. These were cases 

 where the rising sun cast a long shadow of the 

 ship over the water, and a fog-bank happened 

 to be on the surface where the shadow of the 

 top-sails fell upon it. The rest of the shadow, 

 being projected upon the water, was invisible ; 

 and as the sun rose the shadow disappeared 

 by sinking. This phase of the mirage required 

 a peculiarly exceptional combination of sun- 

 light, sea, and cloud for its production, and is 

 therefore rare. 



Fia. 4. FLYING DUTCHMAN. 



the "Flying Dutchman," which has so long 

 foreboded disaster in cabin and forecastle. In 

 order to condense into one illustration, we 

 have shown in Fig. 4 two separate instances 

 of the mirage. The broken arrows represent 

 the sunlight striking upon the surface of the 

 water and reflected from it. One arrow shows 

 reflection from the sunward side of the ship, 

 projecting a shadow of the vessel, which is 

 right side up, and a part of the reversed shad- 

 ow that would come from the water on the 

 other side of the ship ; but we have made use 

 of the arrow which gives expression to the 

 cause of that shadow to point to another fact 

 that frequently occurs, that of portions of the 

 vessel being seen in different parts of the 

 heavens at the same time. The lower part of 

 the hull and sail will be seen in one place, and 

 the top-sails in another, or the wrong-side-up 

 image is in one place, and the right-side-up 

 somewhere else all of which is due to the 

 distribution of the cloud-screens : one may be 



The arrow in Fig. 4 indicates how the sun- 

 light casts a shadow of the ship, the only vis- 

 ible portion of which is the top-sails, which 

 falls upon a distant fog-bank and sinks into 

 the ocean when the sun has ascended to the 

 angle of the dotted arrow. 



An instance of this kind occurred on Lake 

 Erie, in which the top-sails of a schooner were 

 seen from the harbor of Buffalo just above the 

 surface some distance out to sea, when the sun 

 was near the western horizon, and the weath- 

 er perfectly calm. Several steam-vessels were 

 dispatched to the rescue of the possible sur- 

 vivors of the wreck, only to find that the top- 

 sails had disappeared and a vessel similarly 

 rigged was farther westward. The shadow of 

 the schooner had been cast by the sun toward 

 the city, and a mist resting on the water inter- 

 cepted the shadow of the top-sails, the mist 

 being sufficiently thin to transmit the image to 

 its other side. 



All of those shadows grow larger as the dis- 



