I 



November 3, 1904] 



JVA TURE 



17 



garding the absence of any allied magnetic disturbances 

 during tlie appearance of a vigorous sun-spot from May 19 

 to June 26, 1901. 



Herr Nippoldt questions the advisability of introducing 

 statistical gradations of the magnetic disturbances, and con- 

 tends that the magnetic effect at any one place or at a 

 number of places in approximately the same latitude is, 

 possibly, not a measure of the solar cause. That is to say, 

 an instrument near the poles might register a " great " 

 when the Potsdam or Stonyhurst recorders only registered 

 a " small " disturbance. Consequently, he would urge that 

 when the magnetograph trace shows any marked civer- 

 gence from the normal one might consider that a disturbance 

 had taken place, and he shows, by a reproduction of the 

 " horizontal-intensity " curve obtained at Potsdam on 

 May 30-31, 1901, that a disturbance did take place during 

 the time that the spot which Father Cortie especially dis- 

 cussed was on the sun. 



Finally, he confirms M. Deslandres's opinion that in the 

 future the solar observations should be continuous, and 

 thereby become more strictly comparable with the magnetic 

 records. 



The Third Band of the Air Spectrum. — In No. 16 (1904) 

 of the Comptes rendus MM. H. Deslandres and A. Kannapell 

 publish the resu-lts of a study of the third air band, which 

 occurs in the more refrangible part 

 of the ultra-violet end of the spec- 

 trum (A 3000 to \ 2000), under a large 

 dispersion. 



The apparatus used consisted of a 

 capillary vacuum tube closed with a 

 plate of quartz under a pressure of 

 less than i mm. of mercury, and a 

 spectrograph containing two calcite 

 prisms of 60° and two quartz lenses 

 of 13 metres focal length. The 

 latter produced a dispersion which, 

 in the neighbourhood of N =42,189 

 {\ 2370), gave a separation of 

 0-005 mm. for a difference of o-o6 N. 



The wave-lengths of the lines were 

 obtained by reference to a spectrum 

 of iron, using Kayser's fundamental 

 values for the wave-lengths of the 

 latter, and the authors state that in 

 the individual values obtained for N 

 the first six figures are correct. 



In the results it is seen that, 

 although the lines of the band may 

 be separated into four series of 

 doublets according to Deslandres's 

 law, so that the difference of wave- 

 lengths in each series advances in 

 arithmetical progression, yet the 

 variations from the computed values 

 are greater than may be accounted 

 for by errors of measurement, and, 

 what is more remarkable, the sign 

 of these variations for series i. and 

 obtained for series iii. and iv. 



uplift first occurred. Blocks from the adjacent cliff slipped 

 down over the sand, and the series was then preserved by 

 the Boulder-clay of the Glacial epoch. The wide stretch 

 of coast, from Carnsore Point in co. Wexford to Baltimore 

 in the west of co. Cork, over which this raised platform 

 has been traced, affords ample opportunities for comparing 

 the modern with the ancient features. The authors show 

 that the pre-Glacial sea worked against a cliff about loo feet 

 in height, and consequently advanced slowly, leaving a 

 denuded surface remarkably free from stacks and irregulari- 

 ties. This surface commonly lies about 12 feet above the 

 modern beach. Unfortunately, no trace of fossils has yet 

 aooeared in the old beach-deposits, and the authors believe 

 that even pebbles of limestone have been removed by 

 perflating water. The Boulder-clay above contains the 

 usual if.olluscs, including northern species. 



The pre-Glacial beach is traced into the estuaries of the 

 rivers of southern Ireland ; consequently these inlets are 

 still older. Since they have arisen from the submergence 

 of river-valleys, the river-system and the submergence are 

 of pre-Glacial age. This simple but important observation 

 seems effectually to negative the views of the late Prof. 

 Carvill Lewis and Mr. James Porter (Irish Naturalist, 1902, 

 p. 153), who argued that depcsits tf glacial drift might 

 have turned the lower portions of these rivers into their 

 present north-and-south direction. We are thrown back, 



^ 



Opposite to that 



PRE-GLACIAL TOPOGRAPHY.^ 

 'T'HE beautifully illustrated memoir by Messrs. Wright 

 and Muff, recently issued by the Royal Dublin Society, 

 directs attention to an ancient rock-platform on which 

 Glacial deposits were laid down in southern Ireland. The 

 importance of such observations is clear when we consider 

 the possibility of the preservation of a pre-Glacial, and 

 perhaps Pliocene, fauna in favoured localities beneath 

 the drift. At Courtmacsherry Bay, for example, south- 

 west of Cork Harbour, a well marked rock-shelf occurs 

 about 5 feet above high-water mark. On this rests a 

 raised beach, with ferruginous sand and rows of pebbles, 

 succeeded by the blown sand that accumulated when the 



1 "The Pre-Glacial Raised Brach of the South Coast of Ireland." By 

 W. B. Wrisht and H. B. Muff. Scie>ttific Proceedings of the Royal 

 Dublin Society, vol. x. part ii. (Dublin : University Press, 1904 ) Price y. 



NO. i8.?7. VOL. 71] 



then, upon the view of Jukes in accounting for the courses 

 of the Blackwater and the Lee, and inay see, as the drift 

 is slowly washed away, further and further developments 

 of the pre-Glacial topography of Ireland. We have been 

 apt to assume that the western fjords and rias originated 

 when the glaciers retreated from them and the land sank 

 upon the Atlantic side. It now becomes possible that the 

 tongues of ice spread into pre-existing inlets, banking out 

 the sea, and again admitting it in warmer times. Messrs. 

 Wright and Muff even conclude, from British as well as 

 Irish indications, that " a considerable portion of the coast- 

 line of Southern Britain is of pre-glacial age. The approxi- 

 mation over so wide an area of the sea-level in pre-glacial 

 titiies to that of the present day renders it very probable 

 that Ireland was already insulated before the Glacial 

 Period." 



This only increases the difficulty of assuming an e.xtinc- 

 tion of the fauna and flora of Ireland during the maximum 

 extension of the ice. Many points of cheerful controversy 

 lurk behind this straightforward and descriptive paper. 

 Grenville A. J. Cole. 



