SCIENCE AND POETRY. 



proceed from the water, could possibly be such as to make a real 

 dog behave itself as the dog of the fable did on that occasion. 

 Whether we were fully justified in this condemnation of the 

 ancient fable has been called in question, and some of our readers 

 think that an image may be reflected from the surface of water, 

 under supposable circumstances, with sufficient vividness to justify 

 xEsop, or whoever else was the original author of the fable. 



Instead of stopping here to dispute this point, we shall consult 

 the benefit of our readers better by explaining the principles on 

 which it depends, and indicating some simple experiments which 

 we have ourselves tried, and which any of our readers may easily 

 repeat. 



2. "When light falls upon a plane reflecting surface, the pro- 

 portion of the rays which are reflected is found by observation to 

 be less and less, the more perpendicularly the rays are incident. 

 The actual proportion reflected at different degrees of obliquity,, 

 was determined by Bouguer, for different substances. The 

 results obtained by him in the cases of water and glass are given 

 in the following table, where the angle of incidence means the 

 angle which the incident ray makes with the perpendicular to the 

 reflecting surface. In the fourth column of the table is given for 

 each degree of obliquity the number of rays out of every thousand 

 which are reflected, and in the fifth column, the number which 

 are absorbed. 



3, TABLE, showing the proportion of Light incident on reflecting surfaces r 

 which are regularly reflected at different angles of incidence. 



it appears from these results, that when a ray falls so 

 obliquely upon the surface of water, as to make with the per- 

 pendicular to the surface an angle of 75, and, therefore, with the 

 surface itself an angle of 15, nearly a fourth of all the incident 

 rays are reflected, Hence it is that the image of the banks of a 

 194 



