Suspension Bridges appear to be of very ancient origin: travellers have discovered their existence in South America, in China, in Thibet, and in the Indian peninsula. They are most frequently met with in mountainous regions, and being suspended across a deep ravine, or an impetuous torrent, permit the passage of the traveller where the construction of any other kind of bridge would be entirely impracticable. Humboldt informs us that in South America there are numerous bridges of this kind formed of ropes made from the fibrous parts of the roots of the American agavey (_Agave Americana_). These ropes, which are three or four inches in diameter, are attached on each bank to a clumsy framework composed of the trunk of the _Schinus molle_; where, however, the banks are flat and low, this framework raises the bridge so much above the ground as to prevent it from being accessible. To remedy this inconvenience, steps or ladders are in these cases placed at each extremity of the bridge, by ascending which all who wish to pass over readily reach the roadway. The roadway is formed by covering the ropes transversely with small cylindrical pieces of bamboo. The bridge of Penipé erected over the Chamboo is described as being 120 feet long and 8 feet broad, but there are others which have much larger dimensions. A bridge of this kind will generally remain in good condition 20 or 25 years, though some of the ropes require renewing every 8 or 10 years. It is worthy of remark, as evincing the high antiquity of these structures, that they are known to have existed in South America long prior to the arrival of Europeans. The utility of these bridges in mountainous countries is placed in a striking point of view by the fact mentioned by Humboldt, of a permanent communication having been established between Quito and Lima, by means of a rope bridge of extraordinary length, after 40,000_l._ had been expended in a fruitless attempt to build a stone bridge over a torrent which rushes from the Cordilleras or the Andes. Over this bridge of ropes, which is erected near Santa, travellers with loaded mules can pass in safety.