1854.] On tie Mirage of India. 1G7 



The moving population magnified to giant dimensions and deprived of 

 all distinctness of outline would appear like a dense mass of spectres 

 called from the antipodes or from Hades. The Thames would streak 

 the clouds with its pitchy waters and the ghost-like array of ships 

 would glide aloft among the clouds throwing down from their sails 

 long wavy columns of light, terminating on the earth. 



The effect of mirage is greatly enhanced by the use of a telescope 

 which without unravelling the mystery, brings nearer the objects, each 

 in its proper hue, and greatly increases the beauty of the exhibition. 



I have hitherto spoken of the most common species of mirage, viz. 

 that which is produced by a reflecting stratum of vapour suspended 

 overhead. But I have witnessed another variety, viz. that in which 

 the reflecting surface lies below the object and the spectator's eye. 

 This can be seen only where inequalities of surface occur. I first 

 observed it at the military station of Mhow in Malwa. In riding 

 home at midday in the month of March, when approaching the can- 

 tonment from the southern heights, I saw the church vividly reflected 

 from a wavy vapour, hanging over the lower ground : the church itself 

 standing on an eminence. The effect was precisely that produced by 

 water upon objects standing beyond it, excepting that the strong undules 

 of the vapour did not much disturb the accuracy of the reflection. I 

 have since observed the same effect elsewhere, but not in so remark- 

 able a degree, see PI. X. 



I have also observed upon the Nurbudda and other large rivers that, 

 whereas the nearer current is too rapid and turbid to reflect the rocks 

 upon its banks, the more distant current, equally rapid and equally 

 turbid, presents a perfect reflection of the banks without any waving 

 of outline. This may be attributable to the transparent vapour, 

 ever hanging over streams, acting as a mirror to reflect surrounding 

 objects. Or it may be, that the illuminating rays falling upon the 

 ripples at a very small angle and meeting several successive summits 

 in almost the same line, pursue their onward course almost as from a 

 plane, instead of being dispersed or thrown back by the irregularities 

 of surface. Thus, if the angle of their incidence be of 10 degrees, 

 one or two rays, insufficient to impress the retina of the eye, may be 

 all that reach the organ of vision ; the rest being dispersed on all 

 sides. But if the angle of incidence be of one degree, one ray will 



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