70 ANIMAL INTELLIGENCE. 



the ground rose so that the excavation could not be con- 

 tinued without cutting very deep, involving great labor. 

 The beavers surmounted this difficulty by building a 

 dam about a foot high and then excavating at this high- 

 er level for a distance of about 25 feet. Here another 

 rise took place, and another dam was built about a foot 

 high, and the canal continued for another length of 47 

 feet. In every case where these dams were placed, 

 earthworks were thrown out in a lateral direction for the 

 purpose of collecting the water and draining it into the 

 canals. Here then was a perfect system of locks, which 

 the beavers had wrought out in order to supply them- 

 selves with their winter's supply of food. These dams 

 were worn smooth and rounded at the top where the 

 logs had passed over them. If engineering attainments 

 like these do not indicate the possession of reason, it 

 would be difficult to understand in what reason consists. 

 It is beyond belief that any instinct could have taught 

 them that the strain on their dam could be relieved by 

 throwing up another below it, causing the water to back 

 up against it and thus equalize the pressure. And then 

 to alter the size of the trough on the top, as they do, to 

 regulate the overflow, plainly indicates something more 

 than instinct, since instinct applies only to those situa- 

 tions or conditions that are regular and uniform in their 

 recurrence. But this is an emergency liable to arise at 

 any time, the existence of which the beavers must learn 

 from observation, and to which they must apply the 

 proper remedy in order to preserve their homes from in- 

 jury. Think, too, of an animal having found out how to 

 save labor in transporting his goods by running a canal 

 into the country, building it so as to keep the water at 

 the proper level and overcoming the difficulties of a rise 

 in the ground by throwing up a dam and then excavat- 

 ing at the higher elevation, supplying these channels 

 with water by building earthworks on either side so as 



26 



