230 FORMATION OP IMAGES. 



are in two respects: first, it shows an image behind the 

 glass, when in fact there is, in reality, no such image there ; 

 what is meant to be shown is that the rays enter the eye 

 just as if there were such an image ; and, secondly, the il- 

 lumination from one radiant point only is shown, and of 

 those only that portion that finally enter the eye, while in 

 reality the rays proceed in every direction, both from thai 

 point and from every other, those from each point crossing 

 those from every other point every where and in mil- 

 lions of intersections, which it would be impossible to rep- 

 resent in any drawing. Indeed, the case presents to our 

 conceptions phenomena so marvelous, that if we consider 

 every ray as a distinct and independent undulation, we can 

 hardly picture to our minds such a maze of crossings and 

 interminglings, made without disturbance or confusion, as 

 a possibility. 



If, instead of a silvered glass, forming a proper mirror, a 

 plate of plain glass were to be used, the effect would be 

 substantially the same. It would, in fact, be exactly the 

 same if proper precautions were taken to prevent the trans^ 

 mission of light from the other side of the glass to mingle 

 with and confuse that which w r as reflected, or, rather, to 

 mingle and confuse the two sets of images which they 

 would respectively form on the retina of the eye. The sev- 

 eral rays of light would not confuse or disturb each other 

 at all on their passage through the air. Each would pur- 

 sue its own way unimpeded by the rest, and each set would 

 form its own image on the retina. It is only the mind that 

 would be confused in its efforts to separate and distinguish 

 the images. 



If, now, the reflecting plate of glass, instead of being 

 plane and uniform throughout its Avhole surface, were to 

 be broken up, and the fragments thrown in confusion into 

 a basket, it is evident, as was briefly explained in the chap- 



