for strict adherence to the terms of the treaty concluded in April 1906, and particularly to the inviolability of the frontiers of Nepal, Bhutan and Sikkim. The last two years of the Manchu dynasty witnessed the restoration of China's effective suzer- ainty in Tibet from the border marshes to Lhasa, a result chiefly due to the energetic and capable administration directed by Chao Erh-feng, viceroy of Szechuen.
But the province of Szechuen was among the first to be reduced to anarchy by the upheaval of the revolution of 1911, and after the assassination of Chao Erh-feng, the authority of China as suzerain power in Tibet was speedily challenged and overthrown. When the news of the revolution reached Lhasa, the Chinese garrison hastened to throw off its allegiance and following the example of the troops in China, indulged in lawlessness and looting at the expense of the civil population. The latter, led by the ever-restless lamas, took up arms against the invaders and the Chinese garrison found itself cut off from its base and be- sieged. Desultory fighting continued until the return of the Dalai Lama from India; peace was then (Aug. 1912) locally concluded, under an agreement by which all Chinese troops (with the ex- ception of the Chinese resident's body guard) evacuated the country, departing via India after depositing their arms at Lhasa. By this time China's garrisons had been expelled and her authority overthrown in eastern Tibet by the semi-inde- pendent chieftains of that region. The Government of the republic at Peking, desiring to recover the prestige thus lost, authorized the despatch of a punitive expedition, consisting of forces raised by the military governors of Szechuen and Yunnan. The expedition started from Chengtu in July 191 2 ; it had reached and captured Batang in Aug., when, as the result of representa- tions made by Great Britain at Peking (Aug. 19), its advance was stopped and the project subsequently abandoned.
The British Government, in requesting China to abstain from these military operations in Tibet, took the ground that such action constituted a violation of the treaty of 1906. While China's suzerainty was not disputed, the Government could not consent to the forcible assertion of full sovereignty over a State which had established independent treaty relations with Great Britain. The Chinese Government was therefore invited to negotiate a new tripartite agreement defining the status of Tibet. To this communication China replied on Dec. 23 ; meanwhile the expedition had been countermanded, but desultory fighting con- tinued between Szechuen troops and the Tibetans of the border marshes. The Chinese Government's reply justified its military operations, on the ground that the Tibetan trade regulations of 1906 gave them the right to police the trade marts and protect lines of communication. The republic, it declared, had restored the Dalai Lama to his former position and titles and had no intention of making Tibet a Chinese province, but would scrupu- lously respect the traditional system of Tibetan Government. Reference was made to the Indian Government's unfriendly act in preventing communication between China and Tibet, via India, and the hope was expressed that this policy might be reconsidered; but the Chinese Government saw no reason for negotiating a new treaty. Before the end of the year, the last of the Chinese forces had been driven out of Tibet, and on Jan. ii 1913 the Dalai Lama proclaimed the independence of the country by concluding a treaty with the Living Buddha (Hutu- khtu) of Urga (Outer Mongolia). In April, hostilities were re- sumed by the military governor of Szechuen; at the same time negotiations with the Dalai Lama were opened by President Yuan Shih-k'ai, who sent a delegate to Chamdo to discuss terms of peace. In May the British Government renewed its proposal for a tripartite conference, which was ultimately accepted. The conference opened at Simla on Oct. 13; Great Britain was repre- sented by Lt.-Col. Sir A. H. M'Mahon, China by Mr. Ivan Chen, and Tibet by her prime minister, Long Chen Shatra.
China's position at this conference was generally negative; while promising not to convert Tibet into a Chinese province, the Peking Government asked that Great Britain should respect China's position as suzerain and undertake not to annex any portion of the country. Great Britain proposed the creation of an
Inner and an Outer Tibet, the former to enjoy autonomy, the. latter under Chinese control. The Tibetan representative asked i for complete independence and frontier rectifications. The 1 result of the subsequent negotiations, which continued till July 1914, was a draft treaty, which the Chinese Government declined i to ratify. It provided for Tibetan autonomy and recognized China's position as suzerain power, while limiting the representa- ! tion of that power to a Resident with a suitable guard at Lhasa, j It differentiated between the complete autonomy of Inner and ; the semi-autonomy of Outer Tibet. China's refusal to ratify | this treaty was not due to any definite objection to its specific conditions, but to her unwillingness to accept the geographical ! definition of the frontiers of Outer Tibet, as proposed at Simla. I
After the break-up of the conference, the Chinese Govern- ment agreed to the suspension of all hostilities against Tibet pending a renewal of negotiations, and for the next three years a state of armed vigilance was maintained on the Szechuen border. In July 1917, however, a fresh cause of strife occurred in the arrest of two Tibetans by Chinese troops near Chamdo. The Kalong Lama's request for negotiations on the subject was refused, and the armistice was broken by the Chinese general commanding in the marshes, without reference to Peking. In the fighting which ensued, the Tibetans proved victorious; by Feb. 1918 the Chinese garrison at Chamdo was surrounded, and the whole country to the eastward, as far as the right bank of the Yangtse, in the hands of the Tibetans. Chamdo sur- rendered in April, and the Chinese proposed to negotiate for peace. In July an armistice was arranged, at the instance of Mr. Teichman, the British vice-consul; this was followed by a peace conference at Chamdo, at which it was agreed to suspend hostilities for a year, the Tibetans retiring within the boundary of Derge and the Chinese to Kansue. In Sept. 1919 the Chinese Government at Peking proposed a renewal of the negotiations abandoned at Simla in 1914 and gave evidence of its desire to put an end to hostilities; on the Tibetan side there were also indications of a desire for peace. The situation, however, was (and remained) complicated and difficult by reason of the fact that the authority of the Peking Government was ignored by the usurping provincial satraps of Yunnan and Szechuen, and also because the delimitations of any permanently satisfactory frontier for Outer Tibet presented serious problems, ethnological as well as strategic and political.
See Blue Book on Anglo-Tibetan Relations (1910); Sven Hcclin, Trans-Himalaya (1913) ; Reginald Farrer, On the Eaves of the World (1917); The China Year Book (1919). (J. O. P. B.)
TIDES (see 26.938). The present century has seen a marked increase in the interest taken among foreign scientists in the study of the tides, while in Great Britain the subject again received much attention after the close of the World War.
Observation. The automatic tide gauges which are distributed along the coasts (in Great Britain very irregularly and chiefly according to the needs or caprices of harbour authorities) require much more attention than it has been the custom to pay to them. The errors in both elevation and time of their elevation-time graphs should be determined by independent observation at least once a day, as such errors very easily attain serious dimensions.
But the outstanding scientific need of the present time is for off- shore observations. Not only do the great tidal movements of the ocean remain practically unobserved, but in the middle of the Irish Sea, for example, there is a discrepancy of 40 m. between the co-tidal lines of different authoritative charts.
Off-shore elevations have been recorded by personal soundings (at the Dutch lightships, for example) but a number of attempts have been made to construct a self-registering gauge which, when placed on the bottom of the sea, will give a continuous pressure-time record. From such a record it is of course easy to pass to an elevation-time relation. Up to 1921 the gauge which appeared to have met with most success was that of M. Pave 1 , of the French Marine, and even this had not worked in water of depth greater than 200 metres.
Continuous current observations are required at all depths. A knowledge of currents is of immense importance both commercially and scientifically, and the effect of currents on mines during the World War caused much attention to be paid to them by naval authorities. Tidal currents are oscillatory, but observed currents have, as a rule, a residual drift which is of particular importance in general oceanographical or fishery research.
Surface currents have been measured by floating logs (as for most of the data published by the British Admiralty) but series of ob-
