346 



NA TURE 



[February 8. 1900 



<o be allowed. Two ideas presented themselves to my mind as 

 to the possible origin of the beading. One was that it might 

 have something to do with the way in which the path crossed a 

 series of electromagnetic waves, like those of light, except as 

 to the scale of wave-length. Another, which seems more pro- 

 bable, is that they are of the nature of the stratified discharge 

 in exhausted tubes. This supposition indeed is not free from 

 difficulty, though I do not think the difficulty fatal. In an 

 ordinary tube it requires a very good exhaustion to get strata 

 as much as an inch thick. But here, at full atmospheric pres- 

 sure, we have strata a foot or more in thickness. However, 

 in a Geissler tube the strata are closer in the capillary part, 

 where the current is concentrated, than in the broad part. It 

 may be that in the discharges, for example, represented in 

 Fig. I, which are unconfined laterally, these wide strata are 

 possible, and if so, the density of the current is small. It has 

 already been remarked that the intensity decreases as we go 

 from the lamp to the ground. It seems that the current is 

 gradually spent in electrifying the air. If this explanation be 

 <orrect, the local discharges represented in Mr. Webb's photo- 

 graphs may not be so dangerous as some of them look. Still, 

 until we know more about the subject, it might be prudent in a 

 thunderstorm to keep a little away from arc lamps in a street. 



If the wireless telegraphy theory which I have ventured to 

 throw out be the true account of the Webb discharges, it seems 

 that by imitating with any necessary modification the receiving 

 apparatus, and introducing a telephone, as has been done with 

 great advantage by M. Turpain in his researches, it might be 

 possible simultaneously to see and to hear a flash of lightning. 



Cambridge, January. G. G. Stokes. 



The Mathematical Tripos. 



On February 15 the reconnnendations of the Special Board 

 for Mathematics on the Mathematical Tripos will be voted on 

 ^y the Senate of the University of Cambridge. With regard to 

 the changes proposed in the general arrangement of the ex- 

 aminations there can be scarcely any difference of opinion. 

 About twenty years ago the advances in mathematical science 

 had reached such a pitch that it was impossible to cover the 

 whole range of mathematics in a single examination, and many 

 a promising mathematician found himself seriously fettered by 

 the necessity of having to confine himself to those parts of the 

 subject which would best enable him to obtain a high place in the 

 examination, and to spend his time in attaining proficiency in 

 rapidly solving certain classes of problems rather than devote 

 himself to specialising in the higher branches of mathematics. 

 It was under these conditions that the Tripos was divided 

 into two parts, the first covering the less advanced subjects, 

 and the second enabling a candidate to specialise in those 

 portions of higher mathematics for which his enthusiasm and 

 ability best qualified him. The further developments of the 

 last twenty years have necessitated an extensive reconstruction 

 of the schemes, and the framers of the present regulations have 

 been at great pains to bring the Mathematical Tripos into line 

 with modern requirements. At the same time it is becoming 

 -daily more and more evident to those competent to judge that a 

 sound training in mathematical methods is of paramount im- 

 portance in the study of applied science, and the regulation 

 allowing candidates to take Part i. in their fifth term should 

 prove of great value to those who wish to study mathematics as 

 A preparation for the subsequent study of physics or mechanical 

 science or even, nowadays, chemistry. 



The abolition of order of merit in Part i. is a logical outcome 

 of the fact that this part does not represent the highest know- 

 ledge of mathematics. In late years the title of Senior 

 Wrangler, which is often regarded in the outside world as the 

 highest honour which Cambridge can confer, has often been 

 bestowed on men who have proved unequal to the task of 

 securing the highest place in Part ii. The announcement that 

 a lady had been placed "above the Senior Wrangler" caused 

 the greatest excitement throughout the country ; but the fact 

 that on another occasion the only candidate who secured a first 

 division in Part ii. was a lady passed almost unnoticed. Still, 

 it cannot but be regretted that because the Senior Wrangler 

 has not always subsequently proved himself the best man of his 

 year, the University should contemplate altogether abolishing 

 the old title of Senior Wrangler, and that even " wranglers," 

 "senior optimes" and "junior Optimes," may soon be a thing 

 -of the past. When the Tripos Was first divided into two parts, 



NC, 1580, VOL. 61] 



one of the mathematical authorities best qualified to judge 

 considered it desirable that the title of Senior Wrangler should 

 be given to the best candidate in Part ii. This was not done, 

 and hence the position of Senior Wrangler has for many years 

 been an anomalous one, and we have been irresistibly drifting 

 in the direction of abolishing the title altogether. But why 

 should not the first division in Part ii. be called "Senior 

 Wranglers ? " The number who obtain a first division in any 

 year is very small, often not more than two, and these are 

 surely no unworthy successors to the senior wranglers of the 

 past. Moreover, by this means the competition for place would 

 be avoided, each candidate being judged on his merits irre- 

 spective of whether he was in a strong year or a weak one, and 

 the present anomaly of the second or third or even lower 

 wranglers in a strong year being better than the senior in a 

 weak one would be obviated. 



Such a proposal is not inconsistent with the changes in the 

 examinations proposed by the Board. The plea for the reten- 

 tion of the old titles is no question of sentiment. The mathe- 

 matical school of Cambridge has, under the "coaching" system, 

 taken a unique position in the educational system of the country, 

 and it is but right that Cambridge honour-men should retain the 

 marks of distinction which at present distinguish them from 

 graduates of modern Universities. These marks of distinction 

 are well known to the world at large, and may enable their pos- 

 sessors to carry greater weight in insisting on the importance of 

 providing efficient mathematical teaching in our schools, and 

 adequate endowments for the mathematical schools of our pro- 

 vincial Uniyersity Colleges. Too often these schools and 

 colleges are controlled by councils and governors consisting of 

 business men, with whom the name "Senior Wrangler" carries 

 weight, but who only look to the " main chance," and who see 

 no use in encouraging mathematics because they do not under- 

 stand it and think it "unpractical." In encouraging the purely 

 experimental side of science there is a danger of neglecting that 

 training which is needed to enable logical conc'usions and 

 practical applications to be deduced from experiments. It is, 

 therefore, important that the old titles should be retained, not 

 only to enable their bearers to point out that they have been 

 trained in the same. school which has produced so many of our 

 best physicists, ialcluding a Maxwell and a Kelvin, and has 

 thus contributed so greatly to the advancement of Applied 

 Science, but also to encourage others to submit to that 

 rigorous mathematical training without the fruits of which even 

 the most practical of " practical men '' would soon come to a 

 standstill. G. H. Bryan. 



Floating Stones. 



The correspondence on "Floating Stones" brings to my 

 mind a phenomenon I often noticed about ten years ago, when 

 my work caused me to spend a good deal of time on the upper 

 reaches of the River Mersey, of patches of earth floating down 

 the river on the surface of the water. This occurred during the 

 early part of the ebb tide and on water obviously contributed by 

 the river. I concluded ^that this earth was detached from the 

 banks during the quiescent period of high water, and that the 

 surface tension of the water was so increased by the strength of 

 the effluents from the manufactories and other sources, that 

 lumps of earth, often several inches in area and of appreciable 

 thickness, were enabled to float. Unless the conditions have 

 since changed, no doubt the same thing may still be observed. 



Coopers Hill, February 3. A. W. Brightm.ore. 



ENGINEERING AT CAMBRIDGE. 



ON Friday, February 2, a large and important addition 

 to the Engineering Department of the University 

 of Cambridge was inaugurated by Lord Kelvin, as a 

 memorial to the late Dr. John Hopkinson, and his son, 

 John Gustave Hopkinson. In August 1898, only a few 

 days before the terrible accident by which he lost his 

 life, Dr. Hopkinson had discussed with Prof. Ewing the 

 rapid growth of this department, and the urgent need for 

 its extension, and had expressed his intention of starting 

 a fresh movement among engineers to secure the neces- 

 sary funds. In October of the same year, Mrs. Hopkinson 

 communicated to the Vice-Chancellor of the University 

 the desire of herself and her son and daughter to give 



