296 



NATURE 



[July 24, 1890 



Reduplication of Seasonal Growth. 



From time to time instances of this in the case of foliage have 

 been recorded by correspondents in the pages of Nature. This 

 year I have noticed not only an unusually early appearance of 

 this in the development of new foliage-laden twigs, as in former 

 years in the oaks, the hornbeams, the elms, and other forest 

 trees ; but, what is more rare with this somewhat exceptional 

 summer, the fruit-trees seem to be expending their reserve energy 

 in a second season o{ flowering. At this moment an apple-tree 

 in my garden presents the curious sight of apple-blossoms side 

 by side with apples more than half-grown, and a rowan-tree 

 laden with nearly ripe fruit has a corymb of flowers on one of its 

 higher boughs. The plum-trees have presented similar abnormal 

 phenomena within the last week or two. The facts are of 

 interest as pointing to considerable interference with the normal 

 cycle of functional change by variations in environment. 



Wellington College, Berks, July i8. A. Irving. 



Chimpanzees and Dwarfs in Central Africa. 



Perhaps Mr. Stanley or Surgeon Parke, if applied to, could 

 throw some more light on the extraordinary statement made by 

 Emin Pasha, recently referred to, which, if it be true, is the most 

 important statement in the whole book. 



It is probable that when Emin Pasha witnessed the torch- 

 bearers, whether chimpanzees or young negroes or dwarfs, he 

 was not alone, and, even though very short-sighted, he would 

 have been able to verify his observation of the torch-bearing 

 animals by reference to those near him. An experienced 

 naturalist like Emin Pasha is not likely to have made the 

 mistake Prof. Romanes thinks he did make — but it is possible. 



Bearing in mind that a large ape is now undoubtedly acting 

 as a signalman (under direction) on a railway at Natal, who can 

 say what the limits of intelligence are in the tribes of Simians ? 



J.F. 



The Perseid Meteors. 



According to Mr. Denning, the radiant of the famous 

 Perseid meteor-shower (which, in his opinion, commences early 

 in July) shifts night after night until about August 20, the 

 principal change being an increasing R.A. The declination 

 also increases, but more slowly. 



I have some reason to think that the true explanation of the 

 phenomena is that there are several radiants almost simul- 

 taneously in action, but which do not attain their maxima at the 

 same data. For this reason I would ask those of your readers 

 who are interested in the subject to watch these meteors 

 carefully on the present occasion, W. H. S. MoNCK. 



Dublin, July 15. 



P.S. — Mr. Denning's Catalogue in Monthly Notices ior May 

 suggests to me the existence of four radiants (each of some con- 

 tinuance) whose approximate positions are 6° + 52°, 20° + 57°, 

 32° + 53°. and 44° + 56°. 



" Wind Avalanches." 



Some of the readers of Dr. Pernter's paper, "A Winter 

 Expedition to the Sonnblick," may perhaps be interested by the 

 following extracts from the Alpine Journal of June 1864. They 

 are taken from a painfully interesting paper by Mr. Cosset, 

 describing a fatal accident on the Haut-de-Cry in February of 

 that year. 



A party of six were crossing a wide couloir, " about 150 feet 

 broad at the top and 400 or 500 at the bottom." The actual fall 

 of the avalanche is thus described: — " Bennen advanced; he 

 had made but a few steps when we heard a deep, cutting sound. 

 The snow-field split in two about 14 or 15 feet above us. The 

 cleft was at first quite narrow — not more than an inch broad. 

 An awful silence ensued . . . broken by Bennen's voice : 

 'Wir sind alle verloren.' . . They were his last words. 1 

 drove my alpenstock into the snow, and brought the weight of 

 my body to bear on it. . . .1 turned my head to see whether 

 Bennen had done the same thing. To my astonishment, I saw 

 him turn round, face the valley, and stretch out both arms. (So 

 in Dr. Pernter's paper, " Their advice is to throw oneself pros- 

 trate, with hands outstretched. ") The ground on which we stood 

 began to move slowly, and I felt the utter uselessness of any alpen- 

 stock. I soon sank up to my shoulders, and began descending 

 backwards. . . . The speed of the avalanche increased rapidly, 



NO. TO82, VOL. 42] 



and before long I was covered up with snow. I was suffocating 

 when I suddenly came to the surface again. I was on a wave of 

 the avalanche, and saw it before me as I was carried down. . . . 

 The head alone was preceded by a thick cloud of snow-dust ; the 

 rest of the avalanche was clear. Around me I heard the horrid 

 hissing of the snow, and far before me the thundering of the 

 foremost part of the avalanche. ... At last I noticed that I 

 was moving slower ; then I saw the pieces of snow in front of 

 me stop at some yards' distance ; then the snow straight before 

 me stopped. ... I felt that I also had stopped, . . . but the 

 snow behind me was still in motion ; its pressure on my body 

 was so strong, that I thought I should be crushed to death." 



Mr. Cosset further remarks: — "The upper stratum of snow 

 was eleven days old. . . . The snow was thawing, and the 

 whole snow-field in a state of uncertain equilibrium. By cutting 

 through the snow at the top of the couloir we cut one of the 

 main points by which the snow of the two different layers held 

 together. . . . The avalanche may have taken a minute to 

 descend ; I can give no correct estimation on this point.'' 



The vividness of the above description, and its complete 

 accord with Herr Rojacher's account given in Dr. Pernter's^ 

 paper, will, I hope, excuse the length of the extracts. 



Otham, Maidstone. F. M. Millard. 



ON THE METEOROLOGICAL CONDITIONS OF 

 DESERT REGIONS, WITH SPECIAL REFER- 

 ENCE TO THE SAHARA.^ 



nPHE arid regions of the world are, speaking roughly,. 



J- distributed in two bands north and south of the 

 equator. They comprehend all inland drainage areas,, 

 or areas where the streams have no connection with the 

 sea, which are also regions where evaporation is in ex- 

 cess of precipitation, for if the latter were in excess the 

 water would rise till it could flow into the sea, as in the 

 case of the great lake region of North America, and the 

 area would no longer be one of inland drainage. The 

 largest of the deserts, the Sahara, is about 3^ million 

 square miles in area, and the area of all the deserts of 

 the world together about 11,500,000 square miles. In 

 other words, over one-fifth of the land of the world has na 

 outlet for drainage to the sea, and in all that area evapora- 

 tion is greater than precipitation. These areas correspond 

 very closely with the regions of the world where the rain- 

 fall is less than 10 inches annually. 



In no place in the world can there be found such 

 enormous ranges of temperature as in these deserts. In 

 the Sahara the temperature sometimes falls from 100° 

 during the day to the freezing-point during the night, 

 due to the great dryness of the atmosphere and to the 

 radiation that takes place from the soil after the sun has 

 set. These inland drainage areas correspond very much 

 in their barometric phenomena. In all desert regions 

 during summer all the winds blow in upon them. In 

 winter the reverse takes place — the winds flow out of 

 them, and that holds good both for the northern and the 



southern hemispheres. This occasions the low rainfall,, 

 for the great majority of these regions are more or less 

 bounded by high hills. The winds arrive at the deserts 



over these hills, and the vapour is precipitated from the 

 atmosphere by the hills, with the result that when the 

 winds reach the interior regions there is nothing left to- 

 be deposited. If there are not hills all round any desert 

 area, then, as in the case of Northern Asia, the winds- 

 pass from a colder to a warmer climate, and as they get 

 to warmer regions they are able to contain more vapour^ 

 and, consequently, no rain is precipitated. 



The author then gave an account of his own views and 

 impressions as to the Sahara. When staying in May last 

 in Algeria, he was anxious to make a trip to the desert,, 

 principally with the object of examining the sand and 

 other deposits. During the Challenger expedition they 

 had found in the bed of the Atlantic for a long distance 



I .Abstract of a Paper read by Dr. John Murray at the meeting of the 

 Scottish Meteorological Society held in Edinburgh on July 14. 



