POWER OF CALCULATION. 463 



upon it rocks or stones (Hall), there is estimation of height 

 or distance, as well as curve, and perhaps impetus or momen- 

 tum. Walruses themselves 'notice exactly the direction 

 and distance of their enemy (man), and emerge at the spot to 

 meet and destroy him ' (Koldewey) ; that is, they observe his 

 exact topographical position, and calculate how far they must 

 swim under the ice, so as to reach him. 



Certain animals, also, form their own estimates of weight, 

 resistance, impetus or momentum, and size. The elephant 

 must calculate weight or resistance in judging of the degree 

 of strength it must put forth to move a timber log or other 

 heavy object : for in all such cases there is a due adjustment of 

 an animal's force, strength or power, to the physical cha- 

 racter of the object to be pushed, lifted, carried, or piled. 

 The ant probably makes a similar calculation when, meeting 

 with a large, heavy, dead beetle, it calls in the aid of its 

 fellows to roll, carry, or push it to the nest. The same ani- 

 mal shows its knowledge of dimension, of length and breadth, 

 of the smallest diameter of an object in the conveyance of 

 booty, or in the dismembering of prey (Houzeau, Watson). 



Horses, mules and camels measure or estimate the size, 

 as well as weight, of their loads, so as to judge of the 

 possibility of their passing through forest openings, gates, 

 or doors, or of their own ability to bear them with com- 

 fort. 



Tame working elephants are in Ceylon employed in a 

 considerable variety of engineering works. In arranging 

 timber, for instance, the animal balances the logs in its 

 mouth, steadying them with its trunk, places them in ex- 

 actly parallel rows, or in superposition, rolls or pushes 

 them with its head or foot, checks any undue c way ' or 

 momentum by its trunk, expresses dissatisfaction at any 

 irregularity, and readjusts until the desired position is at- 

 tained, and all unaided or undirected (Baker). Such opera- 

 tions necessarily involve not only great variety, but great 

 nicety of calculations. It balances water pipes, lays and fits 

 them into each other (Watson) ; it applies its strength at 

 the proper time and in the proper place ('Animal World '). 

 It reaches coin, when it is tethered, by blowing at a certain 



