Images - 



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f 

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Lower part of tank experiment: syrup optically more dense than water and separated from it by a mixed 

 transition layer. A single image in normal position can be seen when the distant object is viewed through syrup 

 or water alone, at (1) or (5) ; but double or triple images, not in normal position, can be seen when the observation 

 is made from a point below the mixed transition layer, at (4) to (2). Draiving modified from Hastings 



be seen. BetAveen 1 and 2 the object is 

 lifted above its true position and in- 

 creased in vertical dimension. At 2 

 three images appear, the middle one 

 being inverted. At 3 the inverted image 

 will be about midway between the two 

 upright images. As the eye is raised the 

 inverted image will approach the lower 

 erect one and join it at 4> which is the 

 transition plane between the syrup and 

 the water. ^Y]len the eve is at the level 



where only pure water is in the line of 

 vision, the object is again seen in its 

 true position and magnitude. When the 

 eye is raised through successive positions 

 opposite the alcohol [lower figure], the 

 whole series of phenomena seen through 

 the sjTup is reversed, not only as regards 

 position, but also in respect to elonga- 

 tion and compression in the vertical 

 direction. The feature of this experi- 

 ment which is of striking interest to the 



ImagQs 



2 TAT 





< 5 



When the observations are made through the upper part of the tank (optically more dense alcohol above less 

 dense water, with a mixed transition layer between), the phenomena are reversed, and mirage effects are seen when 

 the point of observation is above, the transition layer, between (2) and (4). These laboratory observations illus- 

 trate atmospheric mirage, produced by light from distant objects passing through adjoining layers of dense (cool) 

 and rarefied (warm) air. Drawing modified from Hastings 

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