826 



NA TURE 



[December 16, 1922 



assumes, however, that the live load is suddenly 

 applied. If the time taken to apply the load is 

 comparable with the period of vibration of the bridge, 

 this is no longer true, and however fast a train is 

 travelling the time taken to apply the load is con- 

 , and it is not surprising that actual measure- 

 ments of leflectiori show that the stresses due to a 

 train are in many cases but little greater 

 than those due to the same load when at rest. 



( Ine speaker in the discussion at Hull emphasised 

 the importance of minimising corrosion and looked 

 forward to the possible use of stainless steel for 

 bridges ; in the meanwhile he had great hopes of 

 the cement gun, by means of which a thin coating 

 of cement is applied to the iron work. 



A paper by Mr. J. S. Wilson and Prof. B. P. Haigh 

 dealt very fully with the influence of rivet holes, 



not only in bridges but in steel structures in general. 

 This is of importance in the present controversy 

 because of the uncertainty of the allowance to be 

 made for the rivet holes in calculating the stress due 

 to any given load. Calculation indicates thai verj 

 high stresses should occur in the neighbourhood of 

 rivet holes, but from a large number of experiments 

 the authors came to the conclusion that " the metals 

 used in practice have a ductility and other qualities 

 which render them able to eliminate or accommodate 

 these high stresses." 



I he various papers read and the remarks made 

 ii\ the speakers in the discussion all tended to show 

 that the actual stresses occurring in bridge work 

 are considerably Lower than those usually calculated, 

 and that past and present practice allows an ample 

 factor of safety. 



The Alps of Chinese Tibet and their Geographical Relations. 1 

 By Prof. J. W. Gregory, F.R.S., and J. C. Gregory. 



COUTH-EASTERN Asia is a region of interesting 

 '-' geographical enigmas which deal with the 

 contrast between south-eastern and south-western 

 tie eastern prolongation of the Himalaya, the 

 place of the mountains of south-western China in 

 the mountain system of Asia, and the remarkable 

 arrangement of the rivers of south-eastern Tibet, 

 which has been described as one of the most extra- 

 ordinary features of the earth's land surface. These 

 problems are intimately connected with the formation 

 of the basin of the Indian Ocean. 



" Seek knowledge," said Mohammet, " even if it 

 is found in China," and in accordance with that in- 

 junction of the Prophet the authors landed at Bhamo 

 on the upper Irawadi, 50 miles from the Chinese 

 frontier. This port of departure was selected in 

 obedience to the principle of the Burmese proverb 

 that an old road is a fast road ; for the road from 

 Bhamo to the Treaty Port of Tengyueh in south- 

 western China is one of the trade routes of Asia 

 which has been used since prehistoric times. At 

 Tengyueh the Indians who had accompanied the 

 expedition over the frontier mountains were sent 

 back, a Chinese staff being engaged ; permission was 



"lii, 1 d to proceed to Likiang, the administrative 



headquarters near the borders of Chinese Tibet. As 

 part of this road was across unsurveyed country in 

 which brigandage was rife, the authorities insisted 

 on the money of the expedition being sent on either 

 by draft or along the main road. 



The expedition arrived at Likiang before its money, 

 and a further check was threatened by the refusal 

 ■ if tin 1 magistrate to allow the expedition to proceed 

 further north. This decision was found to be in 

 obedience to instructions from the provincial capital, 

 but the magistrate of Likiang ultimately agreed to 

 let the expedition proceed, provided he had no further 

 instructions from the capital, on the receipt of a 

 1 1 ting that the travellers were going on in 

 spite of his warning and entirely at their own risk. 

 Meanwhile a Chinese merchant in the city had agreed 

 to advance half the amount of the draft, and as soon 

 as this was paid the expedition hurried northward 

 into Chinese Tibet to get beyond recall. 



The path taken descended from the plateau into 

 the valley of the Yangtze-kiang where, though 2400 

 miles from the sea, it is still a great river, and was 

 then in high flood owing to the melting of the Tibetan 

 snows. The structure of this valley and of its two 

 parallel neighbours, the Mekong and Salween, was 

 studied in a series of journeys along these rivers and 



1 Substance of a paper read before the Royal Geographical Society on 



over the mountains between them. The inhabited 

 districts along the Salween were smitten with famine 

 owing to the failure of the previous harvest, and 

 work there was impossible. The range of Kagurpu 

 with its pyramidal snow-clad peaks and its great 

 glaciers was inaccessible, as its crest is the forbidden 

 frontier between Chinese and autonomous Tibet. 

 Hence for a study of the mountain structure of this 

 region the expedition turned eastward to the peaks 

 and glaciers between the Mekong and the Yangtze- 

 kiang, crossing passes from 16,000 to 18,000 ft. in 

 height. Bad weather frustrated the attempt to 

 explore the glaciers of Peima-shan and heavy floods 

 hampered the return march to Likiang. Wide 

 tracts of country around Tali-fu, the former Muslim 

 capital which had withstood a siege of eighteen years 

 during the Civil War of 1855-73, were flooded owing 

 to tlie abnormally heavy rains. The caravan had 

 to enter the city by climbing over the city wall, as 

 the north gate was closed to keep out the mischievous 

 spirits from the north which had brought the ex- 

 cessive rams that were threatening the countrv with 

 famine. From Tali the expedition returned bv the 

 main road across Yunnan to the Irawadi in Burma. 



The observations made during the journey show 

 that the geography of Chinese Tibet is the result of 

 mountain formation at two distinct periods. The 

 deep valleys with their intermediate ranges, which 

 are the most conspicuous topographic features, are 

 the result of mountain movements of the age of the 

 Coal Measures. These ancient movements gave the 

 country a geographical grain trending north and 

 south, and the Indo-Malayan mountains have been 

 formed by the excavation of valleys along the weaker 

 layers of the grain. Mountains belonging to a 

 relatively modern date have been formed contem- 

 porary with the upheaval of the Alps and Himalaya. 

 The high peaks of Chinese Tibet rising over 24,000 

 ft. in height are due to these later uplifts. The main 

 axis of the Himalaya passes through Chinese Tibet 

 ami is probably continued through the Nan-shan 

 of southern China to the Pacific. The Burmese 

 and Malay mountain arcs, which are the same age 

 as the Himalaya, represent a loop to the south of 

 tlie main mountain axis like the Persian loop in 

 south-western Asia and the Apennine loop in 

 Europe. The great rises on the floor of the Pacific, 

 which reach the surface in the Hawaiian Islands 

 and the coral islands of Polynesia, are probably the 

 continuation of these two mountain lines, being like 

 them due to the pressure interacting between the 

 northern cap of the world and the tropical or sub- 

 tropical zone. 



NO. 



2772, VOL. 1 IO] 



