REMARKABLE OPTICAL ILLUSION. 33 



indeed,- the arbiter might set aside the opinions 

 of both the disputants, and render it necessary to 

 appeal to some higher authority, 



to beg he'd tell them if he knew 



Whether the thing was red or blue. 



In the course of writing the preceding obser- 

 vations an ocular illusion occurred to myself of 

 so extraordinary a nature, that I am convinced it 

 never was seen before, and I think it far from 

 probable that it will ever be seen again. Upon 

 directing my eyes to the candles that were 

 standing before me, I was surprised to observe, 

 apparently among my hair, and nearly straight 

 above my head, and far without the range of 

 vision, a distinct image of one of the candles 

 inclined about 45 to the horizon, as shown at A 

 in Fig. 2. The image was as distinct and perfect 



Fig. 2. 



