EXTEMPORISED SUSPENSION-BRIDGE. 205 



nically called "canons." These canons are ravines in the rocky 

 ground, with sides almost perpendicular. For the greater 

 part of the year they are dry, but sometimes, and without 

 the least warning, they become the beds of roaring torrents, 

 rising to some thirty or forty feet in height, and carrying away 

 everything before them. 



Over these ravines are thrown suspension-bridges made 

 almost entirely of creepers, and loosely floored with rough 

 planks. Although they are very strong, they appear to be 

 very fragile, and even under the tread of a human being 

 swing and sway about in a manner that always shakes the 

 nerves of one who is unaccustomed to them. Yet, even the 

 mules of the country can cross them, the animals picking their 

 way with the wonderful sure-footedness of their kind, and 

 not in the least affected by the swaying of the bridge. 



Passing from the vegetable to the animal world, we revert 

 to the Driver-ants, which have already been mentioned. It 

 has been seen that their soldier-ants can, with their own 

 bodies, form a tunnel, under the shade of which the workers 

 can pass, and we have now to see how they can, with the same 

 materials, form a suspension-bridge. 



It often happens that on their march they come to water, 

 and, as they always advance with total disregard of difficulties, 

 they must needs invent some very ingenious way of overcoming 

 the difficulty. One of them climbs a branch which overhangs 

 the water, clasps the undermost twig very tightly, and allows 

 itself to hang from it. Another at once follows, and suspends 

 itself from its comrade in like manner, the powerful and sickle- 

 like jaws doing their duty as well as the legs. A chain of Ants 

 is thus speedily formed. "When the lowermost Ant touches 

 the water, it merely spreads all its legs, and awaits the develop- 

 ment of events. Another runs over it, holds to the first Ant 

 by its hind-legs, and stands in the water, spreading its limbs 

 as much as possible over the surface. Ant after Ant descends, 

 until quite a long chain of the insects is formed, and is swept 

 downwards with the stream. By slow degrees the chain is 

 lengthened, until the Ants at its head are able to seize the 

 bank on the opposite side of the water. When they have suc- 

 ceeded in doing so, the bridge is complete, and over that living 

 bridge will pour a whole army of Driver-ants. 



