February 9, 1893] 



NA TURE 



341 



•clearness. The present volume falls in no respect below 

 the level of those which have preceded it. Among the 

 writers of scientific articles are Prof. James Geikie, who 

 <ieals with the triassic system and with volcanoes ; Prof. 

 Knott, who expounds the principles of thermodynamics ; 

 Dr. R. W. Philip, who writes of tubercle ; and Sir F. 

 Bramwell, who has a paper on water-supply. 



Arthur Young's Tour in Ireland (1776-79). Edited, 

 with Introduction and Notes, by A. W. Hutton. Two 

 vols. (London : G. Bell and Sons, 1892.) 

 This reprint will be of real service to all who study the 

 evolution of economic conditions in Ireland, and much 

 of it ought also to excite and maintain the interest of the 

 general reader. Arthur Young, as every one knows, was 

 a remarkably accurate observer of such things as 

 travellers have opportunities of noting, and his book on 

 Ireland is in its own way hardly less valuable than his 

 more celebrated work on France. The work was first 

 published in 1780, in the course of which two English 

 editions and one Irish edition were issued. Since that 

 time it has not until now been reprinted as a whole. Mr. 

 Hutton has done his work as editor admirably, and a 

 most useful bibliography has been prepared by Mr. J. P. 

 Anderson, 



LETTERS TO THE EDITOR. 



[ The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of NATURE. 

 No notice is taken of anonymous communications. \ 



Some Lake Basins in France, 



A FEW weeks since M. Delabecque, Ingenieur des Fonts et 

 Chaussees at Thonon, kindly presented me with a copyof a work 

 issued under his superintendence and to a great extent executed 

 by himself,^ to which I should be glad to call the attention of 

 students of physiography. M, Delabecque, commissioned by 

 the French Government, has made a series of soundings of ten 

 lakes in Fiance, near the Alpine region, and this Atlas records 

 the results of his work. Contour-lines, in most cases 5 metres 

 apart, indicate the forms of the lake-basins ; the use of varying 

 tints in blue makes these more distinct. Chief among the lakes 

 included is the Leman, in the survey of which, as only one shore 

 is French territory, the Swiss engineers have cooperated. A 

 copy of this on a reduced scale, and without colours, appeared 

 in Prof. Forel's book, " Le Lac Leman " (see Nature, Nov. 3, 

 1892). Next in importance come the lakes of Annecy and of 

 Bourget ; the remainder are situated either in the French Jura or 

 on the margin of the outer limestone zone of the Alps, a little 

 south of the Rhone. 



Excluding the Lake of Geneva, which was noticed in the article 

 just mentioned, these lakes are especially interesting for their bear- 

 ing on the difficult problem of the origin of lake-basins. Except 

 the Lac de Bourget, none of these can be said to lie in a great 

 mountain valley, or on the probable track of a great glacier. If 

 then their basins have been excavated by glaciers, we might 

 fairly expect the Alps and Jura to be " spattered " with lakes, for 

 no appeal can be made to exceptional circumstances : while if 

 the contours of their beds present resemblances to those of the 

 Jarger Alpine lakes, such as the Lake of Geneva, the same 

 explanation ought to apply in the main to both groups. 



Without a reproduction of the charts it is impossible to give 

 •more than a rough idea of the evidence which they afford, but 

 the following statements may be helpful. As a general rule the 

 lakes deepen as they broaden, the deepest water being com- 

 ■monly found in the widest part. If in the course of the lake 

 the shores markedly approach so as to form a kind of "narrow," 

 this corresponds with a submerged neck or " col," which sepa- 



' « " Atlas des Lacs Francais, Minislere des Travaux Publics." No 

 S>ublisher's name appears on the sheets, but I am informed by M. 

 Delabecque that the Atlas can be obtained at Georg's Library, Geneva. 



NO. I 2 15, VOL. 47] 



rates the bed into two basins, rising perhaps 10 metres or more 

 above their general level. Not seldom the bed of a lake consists 

 of a linear series, three to six in number, of shallow basins, so 

 that a contour line, drawn along the axis of the lake, undulates 

 up and down with an " amphlude " of from perhaps 3 to 5 

 metres, A rather long, blunt-ended oval is the prevalent form 

 of these lakes, but to this there are exceptions. So far as can be 

 ascertained the contours of the land above the water-line are 

 reproduced beneath it. For instance, under the steep slopes of 

 the Mont du Chat the bed of the Lac de Bourget plunges 

 abruptly down to a depth of over 120 m. (its greatest depth 

 being about 145 m.). 



Of the Jura lakes, the Lac de St. Point (848-95 m. above the 

 sea) is rather more than 6 kilometres long, the general width 

 being rather less than one-tenth of this ; a considerable part of 

 its floor is 30 to 35 metres deep, and its greatest depth is about 

 42 metres. It contains no less than 6 basins, parted by " cols " 

 about half-a-dozen metres above their lowest parts. This lake 

 is on the course of the Doubs, and lies parallel with the general 

 strike of the Jura, i.e. from N.E. to S.W. The Lac de 

 Brenets on the same river, nearly 100 metres lower down, is a 

 narrow, winding lake, roughly 150 metres wide and perhaps 8 or 

 9 times as long. At its upper end is a sharply projecting, rather 

 shallow bay, but the channel of the Doubs can be traced clearly 

 through this, deepening gradually from 5 to nearly 27 metres and 

 the whole lake is evidently only an enlargement of the river. 



The subalpine lakes are no less interesting, and their testimony 

 generally agrees with that summarised above. Want of space 

 forbids us to mention more than the lake of Annecy. This is 

 deepest (about 65 m.) in its northern and widest part (nearest to 

 the effluent). The sub-aqueous contours on the western side are 

 interrupted, to within about 10 metres from the bottom of the lake, 

 by a prominence, just like a drowned hilly spur. The shallowest 

 soundings over this, near its northern (outer) part, are only 

 33 metres, and the ground falls rapidly down from 5 to 55 

 metres. On its northern or "lee" side (assuming a glacier to 

 have followed the course of the water) is a submerged valley 

 over 40 metres deep. The Lake of Annecy exhibits another 

 very singular feature. Near its northern end the bed deepens 

 very rapidly from 30 to 80 metres ; this funnel-shaped cavity is 

 less than 200 metres in diameter, and is probably a submerged 

 swallow hole. These notes may, it is hoped, suffice to indicate 

 the importance of this work. The gratitude of students is due to 

 M. Delabecque for supplying them with a valuable group of facts, 

 the collection of which must have entailed great labour. These, 

 however, appear to me not to lend themselves very readily to the 

 support of the glacial excavation hypothesis ; but to be more 

 favourable to that which regards the larger Alpine lakes as 

 mainly formed by movements of the earth's crust after the 

 erosion of the valleys in which they lie. T. G. Bonnev. 



Dust Photographs. 



In Mr. Croft's paper on "Breath Figures," printed in 

 Nature for December 22 of last year (pp. 187, 188) he states :— 

 "Two cases have been reported to me where blinds with em- 

 bossed letters have left a latent image on the window near 

 which they lay." The statement is not quite clear as I do 

 not understand whether the letters were in contact with the 

 glass or not. 



Perhaps it may be interesting to place on record an observa- 

 tion of my own, made a few years ago, which r.truck me at the 

 time as curious, but which I have not been able to verify since. 



At the stations of the District Railway there is a useful 

 arrangement by which passengers are informed of the destination 

 of the next train. It consists of a shallow box with glass sides 

 into which by a mechanical contrivance boards are let down 

 on which the names of the stations are painted in white letters 

 on a blue ground. Theboard with the words ' Inner Circle' 

 is most frequently exposed. At night the box is (or was) 

 illuminated obliquely on either side by a tolerably powerful lamp. 



One night I was waiting for the train at the Victoria Station, 

 There was some dislocation in the service ; the destination of 

 the next train was uncertain and the box was empty. On 

 glancing at it somewhat sidewa}s I was however astonished 

 to see the words ' Inner Circle ' on the glass side of the box 

 in quite clear dark letters on a pale illuminated ground. I 

 drew the attention of one of the platform officials to it. He 

 saw it with perfect distinctness, and seemed to think he had 



