NATURE 



[May 15, 19^ 



In finally summarising the position of evening edu- 

 cation in London, Mr. Blair concludes with the follow- 

 ing passage (.p. 24):— "A large increase of students 

 in higher institutions, a large extension of premises 

 and improved equipment, a large increase all over in 

 attendance hours per student ... an increased repre- 

 sentation of masters and workmen on advisory com- 

 mittees, with a corresponding increase in the interest 

 of employers, and of expert criticism of work done, all 

 support the view that the period 1904-12 has been 

 characterised by great expansion in quantity and 

 quality of work." 



Since the publication of the report referred to above 

 the education committee of the council has decided 

 upon a comprehensive scheme of reorganisation of 

 the evening continuation schools, which "are in future 

 to be termed "institutes" instead of -schools." The 

 main features of the scheme are the specialisation of 

 the functions of individual schools depending upon 

 the social, educational, and industrial demands of the 

 respective districts, the appointment of a number of 

 "responsible masters" for evening work only, the 

 increased provision of non-vocational education, and 

 definite coordination with higher institutions, such 

 as the polytechnics. It is mainly in respect to the 

 last point that the organisation of London evening 

 education has compared very unfavourably of recent 

 years with the organisation in a number of provin- 

 cial towns. 



The junior technical institutes will be definitely 

 linked up in future with the neighbouring polytechnic. 

 Tlie principal (or head of department) of the higher 

 institution will have the right to visit the junior 

 institute in an advisory capacity, and to offer advice 

 upon the appointment of the sta'ff and upon the fram- 

 ing of courses and syllabuses. Standing local com- 

 mittees will be formed consisting of the principal and 

 heads of departments of the polytechnic and "respon- 

 sible masters " of the junior institutes, in order to 

 cement^ the relationship between the two types of 

 institutions. 



The new scheme as a whole is thoroughly sound, 

 and, if carried out, as there is everv reason to expect 

 will be the case, it will undoubtedly 'have far-reaching 

 beneficial effects upon London education. 



J. Wilson. 



LAW OF THE PAY-STREAK IN PLACER 



DEPOSITS. 1 

 "C XPLAN'ATIONS of the eccentricities of the pay- 

 - streak in placer deposits have long been con- 

 sidered difficult to furnish. Geikie, Beck, Posepny, 

 Locke, Lindgren, and many others have all discussed 

 the subject and acknowledged the fact. Eight 

 years^ residence and study of placer phenomena in 

 the Klondike gold-bearing region of Canada on the 

 part of Mr. J. B. Tyrrell have enabled him to formu- 

 late a natural law respecting: the location of the pay- 

 streak, not only in the Klondike, but also in anv placer 

 region of the world. 



An accurate knowledge of the structure and growth 

 of a valley, comprising the different phases'of its 

 history in detail, always presents geological facts and 

 deductions capable of broad and general application, 

 and these are generally recognisable without great 

 difficulty. After considering the nature and rate of 

 erosion and sedimentation in a given valley under 

 normal stream action, the formation of a V-shaped 

 valley and its transformation into a U-shaped one, and 

 the presence of flood-plains and terraces, the laws 



1 "The Laws ol the Pay-slreak in Placer Deposit 

 trans. Inst. Mm. and Metal'urgy, pp. 593-605. (Lo 



governing the formation and position of the pay-streak 

 in an alluvial plain in the bottom of a valley may be 

 stated as follows : — 



(1) It was formed in the bottom and at the mouth 

 of the V-shaped valley which was the young repre- 

 sentative of the present valley. 



(2) It marks the position formerly occupied by the 

 bottom of that V-shaped valley. 



(3) The gold contained in it was washed out of the 

 surrounding country and collected into approximately 

 its present position before the gravel of the flood- 

 plain (or terrace) was deposited over and around it. 



The practical application of this discovery of 

 identifying nature's way of hydraulicing and storing 

 the gold in the bottoms of the valleys must be welcome 

 to all economic geologists and mining engineers. 



Mr. Tyrrell holds that some 30,000,000?. of gold has 

 been recovered to date from the Klondike region, and 

 that an equal amount no doubt remains to be ex- 

 traded. Some 900 ft. thick of rock-formations have 

 been removed from the Klondike country, and 130 cubic 

 miles of gravel scattered over the 800 square miles of 

 placer deposits, making only one-hundredth of a 

 pennyworth of gold per ton of original rock concen- 

 trated by nature. H. M. A. 



D ] 



2272. VOL. 91] 



By J. B. Tyrrell. 

 1. 1912.) 



THE UPPER AIR DURING FOHN. 



R. H. VON FICKER has made notable additions 

 to our knowledge of Fohn by his contributions 

 on this subject to the Transactions of the Vienna 

 Academy. His researches showed that the Alpine 

 Fohn is the local manifestation of an extensive pheno- 

 menon which is revealed almost simultaneously in places 

 of the same altitude over a large region. In a paper 

 in the Sitzungsberichte of the Vienna Academy, May, 

 1912, he describes observations on Fohn during three 

 balloon ascents from Innsbruck in igioand 1911. It was 

 found impossible to make ascents at the time of actual 

 Fohn at the surface owing to the very gusty character 

 of this wind. In one ascent only was the balloon over 

 the mountains at the time of Fohn, and then it was 

 the plaything of the vertical currents, which, however, 

 were kind enough to spare the balloonists actual 

 disaster. At one time the balloon was carried down- 

 wards 900 m. and up again 1100 m. in the course of 

 five minutes, indicating vertical currents of five metres 

 per second or more. Such information is clearly of 

 importance to aviators, apart from its bearing on' the 

 elucidation of the meteorological phenomenon. 



The general conclusions of von Ficker are that 

 before the outbreak of Fohn at the surface, it is blow- 

 ing over the cold air in the vallevs and plains, the 

 surface of separation between the two currents being 

 frequently marked by strato-cumulus cloud. When the 

 Fohn current crosses the ridges and valleys at right 

 angles it descends on the lee side and ascends on the 

 windward side, with a partial clearing of the cloud 

 in the region of descending air. Fohn is usually dis- 

 sipated by the coming of a north-west wind', the 

 change probably being of the nature of a line-squall. 

 The vertical temperature gradient during Fohn was 

 usually less than the adiabatic gradient'for drv air 

 except when the balloon was carried up and 'down 

 in the vertical currents, but it was greater than the 

 normal gradient. The change of wind direction with 

 altitude was normal, the south-east wind of the lower 

 layers changing to south and south-west winds at 

 higher levels up to 3-4 km. The value of the discus- 

 sion is enhanced by the results of ascents at Munich 

 and observations at Zugspitze (3000 m.) which the 

 author was able to incorporate bv the courtesy of Dr. 

 Schmauss, who is keenly enthusiastic about all upper- 

 air investigation. E GoiD 



