NA TURE 



[NoVEMiihR 4, 1909 



of water between 1880 and 190S is estimated at 20 per 

 cent. 



Other lakes to the north, north-east, and east of 

 Aral show a similar rise during the last fifteen or 

 twenty years. Lake Balkash has been rising since 

 1S90; Lake Aschikul, in the Tschu depression, which 

 was dry in 1888, was full in 1900, and there is a 

 marked rise in many lakes in the Kirghiz Steppe, 

 along the line of the West Siberian railwa}-, and 

 elsewhere. 



The observations of rainfall taken at Barnaul on 

 the upper Ob since 1838 are of great significance in 

 this connection. The annual amount diminished from 

 1838 till 1868, then increased rapidly till 1895, and it 

 has remained high, with small variations, since that 

 year, the highest five year average (to end of 1906) 

 being 1902-6. 



The evidence goes then to show that the supposed 

 continuous drying up of Central .'\sia has no existence 

 in fact, but that variations occur which may or may 

 not be periodic. If they are recurrent, the period 

 must extend over at least sixty years, and its precise 

 length cannot be determined before the end of the 

 twentieth century, at the earliest. 



Prof. Woeikow adds an interesting section on the 

 history of the Sea of .Aral, which has, naturally, im- 

 portant bearings on the question of secular variations 

 of climate. K rise of the river .Amu of only 4 metres 

 above the level of igoi would cause an overflow of 

 part of its waters by the L'sboi to the Caspian, one 

 effect of which would be that the sea of .Aral would 

 become a fresh-water lake. Historical evidence (see 

 Barthold, " Scientific Results of the .Aral Expedi- 

 tion," igo2 ; and "Historical Geography of Iran," 

 1903 : Berthold, by the way, is of opinion that the 

 climate of Iran and Turan, so far as can be gathered 

 from historical evidence, has remained practically un- 

 changed for 2400 years) goes to show that from the 

 thirteenth to the end of the sixteenth centuries this 

 overflow actually occurred; and it would seem that 

 this was a period of comparatively high rainfall in 

 eastern Europe and western .Asia. 



.A final section of Prof. Woeikow 's paper deals with 

 the thermal relations of water and air over the Sea of 

 .\ral. Space forbids a summary of the e.xtremely 

 interesting results obtained from Berg's observations, 

 which appeal, perhaps, more to the specialist. 



The definite conclusions set forth bv so high an 

 authority as Prof. Woeikow are of profound signi- 

 ficance. The variations in the breadth of the grass 

 belts between forest and hot desert, whether 

 " savana " or "steppe," afford some of the most 

 complex problems awaiting the geographer; the 

 variation is probably greater the greater the total 

 width of the belt, and the area in which the rainfall 

 oscillates above or below a minimum point determining 

 the possibility of human settlement of one kind or 

 another is probably also greater. If it can be estab- 

 lished that there is in effect no real evidence to show 

 tliat in Central Asia a continuous diminution of rain- 

 fall is going on, but that a period of 30 or 40 years, or 

 even of 300 years, of relatively small rainfall has passed 

 its minimum, and that a similar period of greater fall 

 has begun, then it follows that the historical problem 

 of the depopulation of many of those regions, a 

 problem of which the question of water supply can 

 form only one element, becomes greatly modified. .A 

 tliirty years' drought is no doubt sutTicient to depopu- 

 late any district which has a low rainfall at the best 

 of times, but increased rainfall does not necessarily 

 mean immediate repopulation ; and it does not follow 

 that a region which has been deserted by its popula- 

 tion at one time, through drought or other cause, has 

 remained uninhabitable ever since. -Again, it may be 

 XO. 20S8, VOL. 82] 



that large areas which for fifty years or more have 

 been reg'arded as beyond hope will before long yield 

 to modern methods of development and be added for 

 a .generation to come to the wheat producing, or at 

 least the " ranching " regions of the world. 



It is well that a belief which has often, in the 

 absence of direct evidence, been used to bolster up 

 the conclusion that rainfall was also diminishing a 

 long way from Central .Asia (the writer has heard it 

 seriously used to support the contention that dimin- 

 ished yield of wells sunk in the chalk of south-eastern 

 England was due to secular change of climate) 

 should be definitely disposed of irrespective of its irre- 

 levance. .Assuming that no case of constant progres- 

 sive diminution of rainfall in any part of the world 

 has been established, and that none is now likely to 

 be established, the problem seems to be to ascertain 

 the nature and duration of these variations extending 

 over long intervals of time. .Are they periodic? if so, 

 what is the length of period? What is the current 

 phase at different parts of the earth's surface, and to 

 what is the difference due? Central .Asia has appa- 

 rently just passed a minimum phase — has Central 

 .Africa just passed a maximum? .Apparently fifty 

 years of observation will be required to settle these 

 questions. H. N. D. 



NOTES. 



Sir Joseph L.^rmor, Prof. Felix Klein, and Prof. H. 

 Poincar^ have been elected honorary members of the 

 Calcutta Mathematical Society. 



The new rooms of the Royal Society of Edinburgh will 

 be inaugurated on Monday next, November 8, when Sir 

 William Turner, K.C.B., F.R.S., president of the society, 

 will deliver an address, and a reception will be held. 



Prof. K. Schwarzschild, director of the Gottingen 

 Observatory, has been appointed to the directorship of the 

 Royal .Astrophysical Institute of Potsdam, rendered vacant 

 by the death of Prof. Vogel. His position at Gottingen is 

 to be filled by Dr. J. Hartmann, hitherto an assistant at 

 the Potsdam institution. 



The first fellowship established under the will of the late 

 Dr. Sorby, F.R.S., of Sheffield, as reported in our issue 

 of July 8 (vol. Ixxxi., p. 42), has been awarded by the 

 joint committee nominated by the Royal Society and the 

 University of Sheffield to Dr. Jocelyn F. Thorpe, F.R.S., 

 who will engage upon a research on the chemistry of the 

 imino-compounds. 



A Reuter message from New York states that Mr. J. D. 

 Rockefeller has made a donation of 20o,oooZ. in support 

 of a commission of eminent medical men to investigate the 

 hook-worm disease, which is prevalent in the rural districts 

 of the southern States. 



.A MEETING to inaugurate the new observatory and 

 meteorological station of the Hampstead Scientific Society 

 will be held on Saturday, Jvovember 6, at 3.30 p.m., at 

 Heath Mount School, Heath Street, Hampstead. Mr. 

 P. E. Vizard will take the chair, and the speakers will 

 be Dr. F. Womack and Dr. H. R. Mill. 



The eighty-fourth Christmas course of juvenile lectures, 

 founded at the Royal Institution in 1826 by Michael 

 Faraday, will be delivered this j'ear by Mr. W. Duddell, 

 F.R.S., his subject being "Modern Electricity." The 

 course, which will be experimentally illustrated, will com- 

 mence on Tuesdaj', December 28, and will be continued 

 on December 30, 1909, January i, 4, 6, and 8, 1910. 



