We have seen (p. 114) that the first suspension bridges were of two sorts: (_a_) long branches which had grown across rivulets and chasms; (_b_) thick and tough creeping plants by which many forest trees were festooned to one another. It is a vast evolution from these natural things to the art of Ulric Grubenmann, the forerunner of metal suspension bridges.[52] Unfortunately it is also an evolution which we cannot follow through many consecutive phases, artists and historians having failed to record its growth. We cannot suppose that the ancients neglected suspension bridges; from the spider alone they must have learnt that pendent ropes made a good bridge; but we know not what they achieved in this airy handicraft. Many people of to-day show in primitive hammock-bridges that their ancestors were influenced by the work of spiders. In countries so far apart as China and Central Africa and Northern India, for example, there are hammock-bridges of cane and osier, netted elaborately at the sides and swung by bamboo cables, as in China, or by ropes made from the silky fibres of the Nilgiri nettle, as in the Bermulda Hills. Whatever sort of primitive rope is employed, its first model was the gnarled and twisted stem of a vine-like creeping plant. Perhaps the most ancient suspension bridge in China is the one known as _Liu Soh_ or _Lew saw_, literally a slip rope. A bamboo cable is fixed from side to side of a ravine, not in a level line, but a little aslant, so as to form a mild sort of switchback. A traveller carries a wooden saddle with a deep groove in it; the groove fits the bamboo cable, and straps fasten the saddle and give confidence to the jockey, who travels at a rapid speed when he is fat. On his return journey he is pulled up the bridge by ropes. In the mountains of Sichuan there are hundreds of these single cable-bridges.[53] What are they but lianes and vine stems _plus_ a little human primitiveness?