ROOF OF NEST WATER-PROOF. 41 



tions, providing materials^, guarding their infant pro- 

 geny^ collecting food^ and defending themselves against 

 their enemies, their instincts are admirable, and 

 assume the appearance of order and design ; but take 

 one of them away from its fellows, and place it in a 

 situation entirely new to it, it has no judgment to 

 direct its conduct, or to extricate it from its unfortu- 

 nate lot ; therefore, its habits, however wonderful, 

 (and they are truly so, as will be further shown,) are 

 only the irresistible effects of impulse, and performed 

 without a knowledge of the future, or a motive for 

 choosing one mode of building in preference to an- 

 other. 



Great precautions are taken to keep the apartments 

 dry ; the area mentioned before forms a roof that is 

 water-proof, and would carry off any water that 

 might accidentally enter the dome, by a communica- 

 tion with some of the large, subterraneous passages 

 that run at the base in various directions : these are 

 lined with the same kind of clay of which the hill is 

 composed, and ascend the inside of the outward shell 

 in a spiral manner, winding round the whole build- 

 ing till they reach the top : they intersect each 

 other at different heights, and open either into the 

 dome immediately, or into the interior building. 

 From every part of the large galleries issue small 

 pipes, or lesser galleries, leading to different parts 



