HABITATIONS OF INSECTS. 515 



outlets by which the Termites carry on their depreda- 

 tions at a distance from their habitations. They run in 

 a sloping direction under the bottom of the hill to the 

 depth of three or four feet, and then branching out hori- 

 zontally on every side, are carried under ground, near 

 to the surface, to a vast distance. At their entrance 

 into the interior they communicate with other smaller 

 galleries, which ascend the inside of the outer shell in a 

 spiral manner, and, winding round the whole building 

 to the top, intersect each other at different heights, 

 opening either immediately into the dome in various 

 places, and into the lower half of the building, or com- 

 municating with every part of it by other smaller circular 

 or oval galleries of different diameters. The necessity for 

 the vast size of the main underground galleries evidently 

 arises from the circumstance of their being the great 

 thoroughfares for the inhabitants, by which they fetch 

 their clay, wood, water, or provision; and their spiral 

 and gradual ascent is requisite for the easy access of the 

 Termites, which cannot but with great difficulty ascend 

 a perpendicular. To avoid this inconvenience, in the 

 interior vertical parts of the building, a flat path-way, 

 half an inch wide, is often made to wind gradually, like 

 a road cut out of the side of a mountain, by which they 

 travel with great facility up ascents otherwise impracti- 

 cable. The same ingenious propensity to shorten their 

 labour seems to have given birth to a contrivance still 

 more extraordinary. This is a kind of bridge of one 

 vast arch, sprung from the floor of the area to the upper 

 apartments at the side of the building, which answers 



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