March ii, 1880] 



NATURE 



443 



to represent both on a skeleton map as constituting one 

 great range or axis of elevation. The sub-Himalayas consist 

 of rocks of different age from those of the Himalayas, and there 

 is some reason for believing these hills to be of later origin than 

 the main chain ; they are therefore represented in our map as a 

 distinct range. 



It would take too much space to criticise at any length Mr. 

 Trelawney Sannders's Tibeto-Himalayan system (Geographical 

 Magazine, 1877, p. 1 73). This system proposes to resolve "the 

 leading outlines of the vast mass of which it treats into four 

 great chains, with their outer slopes and intermediate valleys or 

 plateaus." The chains are called the Kuenluen, Karakorum- 

 Gangri, and Northern and Southern Himalaya. Now the 

 greater part of the Tibetan area, including, at all events, all east 

 of the meridian of 82° E. long., is too imperfectly known for 

 any positive assertion to be made as to the number of ranges. 

 In the better known western part of the area one fact alone, the 

 omission to include as one of the main structural features, the 

 range between the Indus and Shayok, shows the description and 

 delineation to be geographically incorrect. The range omitted 

 is at least of equal importance with some of those included. 

 There are many other points open to question, such as the 

 representation of the ranges north and south of Cashmere, as 

 mere continuations of the so-called Northern and Southern 

 Himalaya. In short the system will not fit into the only part of 

 the area with which we have any adequate acquaintance. The 

 accompanying map is doubtless an admirable sketch of the 

 Himalayas as they would be if reconstructed according to Mr. 

 Trelawny Saunders's hypotheses, but I think all who have ever 

 been in those mountains will agree with me that it is not an 

 accurate representation of the range as at present existing. 



In conclusion I must decline to reply to any further remarks 

 on this subject from Mr. Trelawney Saunders. It appears to me 

 that Mr. Medlicott and I are entitled to express an independent 

 opinion on the physical geography of the Himalayas without 

 being accused of adopting an antiquated theory. In addition to 

 the geographical data known to Mr. Saunders we have some 

 acquaintance, imperfect, it is true, but still of importance, with 

 the geology, and we have both some slight personal knowledge of 

 portions of the range. Under these circumstances we have not 

 adopted the theory advocated by Mr. Saunders simply because 

 we consider it not supported by sufficient evidence. 



February 29 W. T. Blanford 



[This correspondence must end here. — Ed.] 



Tidal Phenomenon in Lake Constance 

 Les mouvements de la glace et de l'eau du lac de Constance 

 deems par M. S. J. Capper (Nature, vol. xxi. p. 397) ne 

 doivent pas etre rapportes a une maree luni-solaire, ce pheno- 

 mene etant inappreciable sur un lac dans si petites dimensions. Je 

 me fonde sur les resultats negatifs que j'ai obtenus sur le lac 

 Leman, plus grand en longueur et en surface que le lac de Con- 

 stance. En utili-ant les traces de mon limnographe de Morges 

 qui me permet d'evaluer a chaque instant a un millimetre pres, 

 la hauteur du lac en choisissant les circonstances les plus favor- 

 ables, calme absolu de l'eau, et epoquesde syzygie, je n'ai jamais 

 pu reconnaitre de traces de marees luni-solaires. 



En revanche les mouvements de balancement de l'eau que 

 nous etudions depnis bien des annees sous le nom de seiches, 

 expliqueraient facilement une partie des fails signales. Les 

 seiches, comme on le sait, sont un mouvement de balancement 

 de toute la ma-se du lac, qui oscille d'une extremite a l'autre 

 comme le fait l'eau d'une cuvette ou d'une baignoire. II est vrai 

 que le rhythme des seiches du lac de Constance, pour autant que 

 je le connais par une seule observation du 14 septembre 1S74, 

 n'a qu'une duree d'une heure environ, et non douze heures 

 comme l'indique le batelier de M. Capper. II serait fort a 

 desirer, pour 1'interpretation de phenomene. que M. Capper put 

 fournir des donnees et observations aussi exactes que possible des 

 mouvements qu'il decrit. F. A. Forel 



Morges (Suisse), 3 mars 



The Tay Bridge Storm 



A brief account of the results obtained from the examination 

 of a large number of observations referring to the storm on 

 December 28, 1879, may be of interest even to your non-meteoro. 

 logical readers. 



At 6 p.m. on the evening of that day, as will be seen by the 



accompanying chart, Fig. 1, the centre of a cyclone of consider- 

 able intensity was situated close to Stornoway. By 8 a.m., the 

 29th the centre had moved a distance of about 8co miles to the 

 vicinity of Stockholm, which gives the high mean velocity of 58 

 miles an hour. But by a method detailed below, it is found 

 that between 6 p.m. and 8-15 p.m. the centre moved along the 

 north of Scotland at the rate of 62 miles an hour, which is, I 

 believe, the highest on record in this country. No precise relation 

 has yet beenitraced betw een the velocity of a cyclone centre and 

 the strength of the wind in it. In any part of a cyclone the 

 velocity of the wind is undoubtedly principally dependent on 

 the closeness of the isobaric lines, but there is a good deal of 

 evidence to show that when the velocity of the centre is very 

 great, the strength of the wind for any given gradients is in- 

 creased, or at all events becomes more squally and gusty. 



In this ca-e the steepest gradient was down the west of Scot- 

 land, but only amounted to about 013 inch per 50 miles, which 

 is a very moderate amount for a winter storm. 



An important result of recent research has been the discovery 

 that every cyclone is divided into two parts by a line drawn 

 through the centre, more or less at right angles to the direction 

 of its motion, at all points in front of which the barometer is 

 falling while it is rising in rear. This line marks out w hat is called 

 the trough of a cyclone, and while the front and rear present 

 marked contrasts both as regards the in-curvature of the wind, 

 and still more as regards their physical appearance, it is also 

 found that the passage of the actual trough all along its southern 

 portion, except very near the centre, is marked by violent squalls. 

 In the accompanying diagram the position of the trough at 6 p.m. 

 can only be drawn approximately from general considerations 

 as passing down the west of Scotland, but at S. 15 P.M. I have 

 fortunately been able to locate it with great accuracy. At that 

 time the barometer turned upwards at Wick, and almost at the 

 same moment my own barograph in London also turned upwards 

 with the characteristic squall. The line of the trough joining 

 those two points would then be about thirty-three miles east of 

 Dundee, and by combining it with the previous data, the high 

 centre velocity of sixty-two miles an hour was obtained. 



