HABITATIONS OF INSECTS. 515 



meters. The necessity for the vast size of the main 

 underground galleries evidently arises from the cir- 

 cumstance of their being the great thoroughfares for 

 tlie inhabitants, by which they fetch their clay, wood, 

 water, or provision ; and their spiral and gradual as- 

 cent is requisite for the easy access of the Termites, 

 which cannot but with great difficulty ascend a perpen- 

 dicular. 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 impracticable. 

 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 

 the purpose of a flight of stairs, and must shorten the 

 ^ii stance exceedingly in transporting eggs from the 

 joyal chambers to the upper nurseries, which in some 

 hills Avould be four or five feet in the straightest line, 

 and much more if carried through all the winding pas- 

 sages which lead through the inner chambers and apart- 

 ments. Mr. Smeathmau measured one of these bridges, 

 which was half an inch broad, a quarter of an inch thick, 

 and ten inches long, making the side of an elliptic arch 

 of proportionable size, so that it is wonderful it did not 

 fall over or break by its own weight before they got it 

 joined to the side of the column above. It was strength^ 

 cned by a small arch at the bottom, and had a hollow 

 or groove all the length of the upper surface, either 

 made purposely for the greater safety of the passengers. 



