February 13, 1902J 



NA TURE 



347 



the effect of fjie different aspects of what may be called 

 polarised cowls or terminals, i.e. cowls or terminals the 

 action of which is different jvccording to their position with 

 regard to the direction of the wind. One of the most 

 conspicuous is that of a cou4 of the same shape as the 

 torpedo air extractor now so much in use on railway car- 

 nages. From the numbers given, the apparatus is 

 clearly much more effective when the wind crosses the 

 opposed cones than when it passes along the cones and 

 through the ring, and this difference of action is definitely 

 characteristic of the two positions of the cowl. 



Towards the end of thf period of ils labours the com- 

 mittee began to approach the question in more academic 

 or philosophical fashion. Experiments with smoke .were 

 tried to see how cowls and terminals I'eally acted. The 

 committee was thus led to test the effect of successive 

 variations of the number, size, position and arrangement 

 of different modifying elements, such as a flange at the 

 rim of the orifice or at a measured distance from it, a 

 set of " feathers " arranged round the orifice and " louvre " 

 bands or caps above it. A series of experiments to 

 test the effect of the variation of a single element 

 was carried out on single days and the results plotted 

 in curves for the single varying elements. Here we 

 have as results only gahanometer readings for different 

 batteries, so to speak, but for batteries varying 

 only in a single particular, and from such information 

 effective inferences can be drawn about the action of 

 the battery. These results afford the best material in 

 the report for the scientific study of the action of cowls. 

 It still remains only material, and requires working up 

 with due regard to the theoretical considerations referred 

 to. But some practical results follow directly. F"or 

 example, a flange surrounding the orifice of the pipe 

 diminishes the aeromotive force produced by wind pass- 

 ing over it, and if sufficiently extended practically an- 

 nihilates the flow. It is not by any means impossible 

 that an examination of these curves may lead to further 

 investigation of the laws of flow through tubes under 

 the action of passing wind. It is a subject whi,ch pre- 

 sents all the difficulties of the corresponding electrical 

 problems, with some added in consequence of the inertia 

 of the moving fluid, but it is of great practical as 

 well as theoretical importance, and the report will have 

 done good service if it attracts attention to the further 

 study of the subject from this aspect. 



One of the most amazing facts about the histoiy of 

 science in the last century is the little progress made 

 in our knowledge of pneumatics compared with the ad- 

 vances in our knowledge of the flow of electricity, which 

 still borrows its language for practical purposes from 

 the older and now almost neglected study of the flow of 

 fluids. The theoretical development of electricity can be 

 attributed to Faraday's experiinental investigation of the 

 laws of electromagnetic induction. The flow of air along 

 pipes in consequence of wind passing over the top may 

 fairly be regarded as a case of pneumatic induction. The 

 experiments of the cowl committee, if they have not 

 succeeded in classifying these inductive effects into 

 laws, have reopened the study of the subject, and at 

 least give evidence that it is not the fulness of experimental 

 knowledge that has dissuaded the intellects of the students 

 of our laboratories from its investigation. 



\V. N. Shaw. 



GOLD IN INDIA. 

 INDIAN gold is attracting the attention of the Geo- 

 ■'■ logical Survey of India. In Nature for May 9, 1901, 

 we directed attention to Dr. F. H. Hatch's report on the 

 Kolar gold-field in Mysore. We have now received 

 reports on the gold-fields of Wainad, by Mr. H. H. 

 Hayden and Dr. Hatch, and on some auriferous localities 

 in north Coimbatore, by Mr. Hayden {Mem. Geol. 

 NO. 1685, VOL. 65] 



Survey, India, vol. .xxwii. part ii. 1901,) These districts 

 lie to the south of, ^Vlysore. The extraordinary dis- 

 crepancy between reports made on various properties of 

 Wainad by mining experts and the actual results sub- 

 sequently obtained have-justified independent investiga- 

 tions on the' part of the Indian Government. It is re- 

 corded that in 1880 nurnerous companies, having an 

 aggregate capital of more than four million pounds, were 

 floated on the London market ; of these only three 

 companies retam their properties, and no work has been 

 done for a number of years. The question to be solved 

 was whether improved modern methods might render it 

 possible to revive the gold-mining industry in the area. 

 Dr. Hatch's report is, however, unfavourable. Dealing 

 specially with two mines, he finds that ore does not occur 

 in payable quantity, and he is unable to recommend 

 further prospecting. Mr. Hayden gives an interesting 

 historical sketch of the gold-mines, and describes in 

 some detail the geological features of the district. The 

 country-rock is in most cases biotite gneiss ; this has 

 been affected by a series of parallel fissures which run 

 obliquely to the direction of the foliation, and in these 

 fissures the vein-material was deposited. Pyrites proved 

 to be the chief source of the gold, but the richer ore- 

 bodies are small irregular patches, not of sufficient 

 e.xtent to be of material value. 



Mr. Hayden remarks that there are few auriferous 

 areas in India, poor as well as rich, that have not at some 

 period or other been exploited by the natives ; but the 

 fact that gold was obtained in sufficient quantity to cover 

 the expenses and leave a margin of profit, does not in 

 itself justify the belief that a good margin of profit would 

 be obtained if modern methods of working were adopted. 

 .Many of the reefs were probably mined by forced labour 

 or by slaves. Thus one of the Wainad reefs, which was, 

 perhaps, worked more extensively than any other, has 

 given, from nearly 200 samples, an average yield of 

 about two pennyweights of gold to the ton of ore. In 

 Coimbatore there are numerous old native workings for 

 g'old, but they are, as a rule, small and unimportant, and 

 the ore-bodies are either very thin or barren. Further 

 prospecting, however, appears to be advisable in this 

 district. 



NOTES. 



The attendance of the Prince of Wales at the meeting of the 

 Royal Society on Thursday last is an event which we have 

 pleasure in recording. His Royal Highness was formally ad- 

 mitted as a Fellow pf the Society, and remained throughout 

 the meeting. At the close of the proceedings he was invited by 

 the president to address the meeting, and in response he said : — 

 "Mr. Pre.sident, my lords and gentlemen, — It gives me very 

 great pleasure to have been able to come here today and to be 

 formally admitted as a Fellow of this ancient and distinguished 

 society. But, as you conferred the honour of Fellowship upon 

 me some eight years ago, I really ought to apologise for not 

 having presented myself before. I can only sayil am indeed 

 proud that my name should be added to those on your illustrious 

 roll, which has been inscribed by nearly every Sovereign since 

 the reign of Charles XL, and by all the most distinguished men 

 of science since those days, such as Wren, Newton, Davy, 

 Faraday, Darwin, and many others. I would wish to ofler my 

 sincere thanks to Sir William Crookes for his most interesting 

 lecture, which I am sure we have all listened to with great 

 pleasure. If I may be allowed to do so, I should like to con- 

 gratulate him on his power of treating such an abstruse 

 question (for I must confess that the title rather alarmed me> 

 so as to make it intelligible and attractive to those who, like 

 myself, unfortunately cannot lay claim to much scientific know- 

 ledge. But, while fully realising how far beyond my reach this 



