Jud] AND SYMBOLS. 185 



says, " on their predatory expeditions in company, and previous 

 to the commencement of their operations they hold a kind of 

 mock-fight upon the rocks in order to determine their relative 

 strength. When this has been fairly ascertained they advance 

 to the brink of the precipice, and taking each other by the tail, 

 the weakest descends first, while the strongest, forming the last 

 in the row, suspends the whole number till the foremost has 

 reached their prey." Then they determine upon a " voluntary 

 winding up." A signal is now given, on which the uppermost 

 fox pulls with all his might, and the rest assist him as well as 

 they can with their feet against the rocks. In this way they 

 make off and proceed from rock to rock, until they have pro- 

 vided themselves with a sufficient supply, like a number of 

 cunning promoters of companies pouncing down upon the 

 public from the altitudes of magnificent schemes and vast pro- 

 fessions. E. 



Comparison and Judgment. 



The estimation of distance and of size of objects depends on 

 numerous circumstances ; these are, the visual angle, the optic 

 angle, the comparison with objects whose size is familiar to us, 

 the diminution of the precision of the image by the interposi- 

 tion of a more or less vaporous medium. When the size of an 

 object is known, as the figure of a man, the height of a tree, or 

 of a house, the distance is estimated by the aperture of the 

 visual angle under which it is seen. If its size is unknown, it 

 is judged relatively to that of objects which surround it. A 

 colonnade, an avenue of trees, the gas-lights on the sides of a 

 road, appear to diminish in size in proportion as their distance 

 increases, because the visual angle increases ; but the habit of 

 seeing the columns, trees, &c., in their proper height leads our 

 judgment to rectify the impression produced by vision. Simi- 

 larly, although very distant mountains are seen under a very 

 small angle, and occupy but a small space in the field of view, 

 our familiarity with the effects of aerial perspective enables us 

 to form a correct idea of their real magnitude. The optic angle 

 is also an essential element in appreciating distance. This 

 angle increasing or diminishing according as objects approach 

 or recede, we move our eyes so as to make their optic axes 



