812 



REPORT— 1900. 



4. Journeys in Central Asia. By Captain Et. II. P. DeasV. 



Captain Deasy's paper deals with explorations in Western Tibet and Chinese 

 Turkestan, begun in 1S9G. The most important features of this explorer's work 

 are, first, the extensive use of triangulation for determining' longitudes from 

 peaks, fixed by the Great Trigonometrical Survey of India, and heights ; secondly, 

 the discovery of the sources of the Khotan River; and thirdly, the detailed survey 

 of that exceedingly difficult mountainous region, the hitherto unknown stretch of 

 the Yarkand River. 



The contiuued opposition of the Chinese added considerably to the physical 

 difficulties encountered, and resulted in the explorer and his assistant being 

 incapacitated from work by severe illnesses. The latter compelled Captain Deasy 

 to return to India much sooner than he had intended. 



It may be of interest to note that the heights of about 250 peaks were 

 determined, and over 40,000 square miles of country surveyed. Much valuable 

 assistance was rendered by the Indian Government, especially by the Surveyor- 

 General, and seTcral officers of the Foreign Department. Captain Deasy is very 

 grateful for this, as well as for the services of the native topographers, kindly lent 

 by Colonel Gore, R.E., now Surveyor-General of India. 



5. Large Earthquakes recorded in 1899. By Johk Milne. 



In 1899 at Shide, in the Isle of Wight, 130 earthquakes were recorded. The 

 greater number of these were also observed at Ivew, whilst very many of them 

 were common to registers from Canada, the Cape of Good Hope, India, Java, 

 Japan, and other distant countries. 



Analysis of these records has increased our knowledge respecting the rates at 

 which motion is transmitted through our world, and indirectly thrown new light 

 upon its rigiditj^ The arcual velocity of surface waves has been investigated, and 

 new rules based on these investigations have been formulated for determining the 

 position of earthquake origins. It has, for example, been shown that the distance 

 of an origin from a given station can be determined either from the interval by 

 which the preliminary tremors outrace the larger surface waves or from the interval 

 between the arrivals of waves which had travelled from their origin round the 

 world in opposite directions. 



With this knowledge it is frequently possible for an observer in any part of the 

 world to name the district from which an earthquake recorded at his observatory 

 has originated. 



One series of observations showed that the amplitude of the large waves 

 of earthquakes decreased more rapidly when traversing suboceanic paths than 

 when they radiated over continental surfaces. In discussing the nature of 

 large waves this observation on the damping effect of oceans was used as an 

 argument that this form of seismic movement represented gravitational surface 

 waves rather than the outcrop of distortional waves propagated through the body 

 of the world. 



One hundred and twenty-five out of the 130 records considered represented 

 disturbances which had suboceanic origins. The principal of them may be grouped 

 as follows: — 



1. North-eastern Pacific, W. of British Columbia 



2. East Mid Pacific, W. of Southern California 



3. East Southern Pacific, W. of Peru and Chili 



4. West Pacific, ofE Japan .... 



5. West Mid Pacific, near Java 



C. Mid Indian Ocean 



7. North Atlantic, east side .... 



8. West North Atlantic and West Indies . 



9. Mid Equatorial Atlantic .... 



14 

 5 

 8 



19 



12 

 9 



17 

 6 

 5 



