In addition to his own itinerary Rockhill mentions three other routes through eastern Tibet leading to Lhasa. By the »Sining-fu high road» we are no doubt to understand the road which is generally used by pilgrims from Mongolia and by the Chinese authorities and the Chinese post travelling to and from Peking. But we may also just as certainly speak of a regular »faggot» of roads, which converge upon Lhasa from different parts of Tsajdam and Koko-nor, most of them merging into a common highway north of the Tang-la. It is in that region that we find the itineraries of Prschevalskij's first and third journeys, Huc and Gabet's journey of 1845, and the route of the Chino-Mongolian mission from Urga to Lhasa in i 873. Rockhill's itinerary lies almost entirely to the west of these. The road which he mentions as running from Lop-nor due south to Lhasa is pretty certainly not in use at the present time; for by making the little deviation through Tsajdam the caravan animals are spared.
Where the mountains, rivers, and lakes do not possess traditional names, Rockhill has hit upon the original and fairly happy idea of giving them native names of an illustrative and characteristic meaning, names as simple and as significant as the traditional names in use amongst the natives.
From Rockhill's description it is evident that grazing is far more abundant in the parts of Tibet through which he travelled than in those which Bonvalot, de Rhins, Littledale, and I explored. It may indeed be laid down as a general rule, that the vegetation grows poorer and scantier from east to west, though this does not hold good throughout Tibet. It is worst on the most central and highest plateaus, but grows more abundantly towards the west; indeed in the high valleys and glens that drain to the Jarkent-darja it is in many localities very good.
What Rockhill says about the climate is very interesting. He speaks of copious downpours and, especially in the southern part of his journey, of plentiful rains. Evidently the part of Tibet which he visited is more plentifully watered than the region to the west of it, as indeed might be expected from its geographical position and from the configuration of the country in relation to the monsoons; moreover it is suggested by the circumstance that the big Indo-Chinese rivers have their sources in that part of the country. Thus the amount of precipitation decreases from east to west and from south to north. Rockhill's observations however afford us confirmation of the existence of a distinctive rainy season, coinciding with the summer months. He found too that most of the watercourses and rivulets contained running water, although he also passed some that were for the time being empty. With regard to the Mur-usu, which he crossed over on the 22nd June, Rockhill says, there were no signs of the river having reached a higher level; this seems to indicate that he saw the river at the time when it was as a fact at its maximum. Neither at the Tschib-tschang-tso or any other lake did he observe any old strand-terraces. This is in some respects surprising, for it is otherwise the rule to find indications of that nature beside all the Tibetan salt-lakes. Generally it may be said that the desiccation of the lakes is increasingly more pronounced in proportion as you advance towards the west; but future and more searching investigations must determine whether the climatic retrogression from moisture to aridity is indeed more pronounced in the west than in the east. From what we
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