May 3, 1900] 



NA TURE 



Les Vteux Arbres de La Normandie. By Henri Gadeau 

 de Kerville. Fasc. iv. Pp. 219 + 352. (Paris: J. B. 

 Bailliere et fils, 1899.} 



This instalment of M. de Kerville's careful monograph 

 contains twenty views of trees from photographs by the 

 author, accompanied by detailed descriptions and histori- 

 cal notes. The work is well and conscientiously done, 

 whilst the illustrations are well selected and admirably 

 reproduced in collotype. The trees here shown include 

 ten oaks, six yews, two beeches, a lime and a poplar. 

 As the photographs of the deciduous trees have been 

 taken in very early spring, before the opening of the buds, 

 their ramification and general architecture are shown to 

 the greatest advantage. With this volume, a propos of 

 a notable oak-tree growing at Isigny-le-Buat, the author 

 includes an interesting account of recorded cases of 

 mistletoe upon oaks in Normandy. He is able to pro- 

 duce evidence in support of some twenty-seven recorded 

 instances. The book will appeal to all tree-lovers ; may 

 it stimulate some to similar studies. We remember to 

 have seen something of the kind for Northumberland 

 nearly thirty years ago in the Transactions of the Tyne- 

 side Naturalists' Field Club. 



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. '\ 

 The Nature of the Solar Corona. 

 I SEE in the recenty-published number of Science Abstracts, 

 No. 802, than there is every reason to think that the corona line 

 is not represented by any dark line in the solar spectrum. I 

 write to call attention to the way this confirms the suggestion 

 that the corona is an aurora round the sun. In the March 

 number of the Annalen der Physik for this year, p. 462, Herr 

 Cantor describes experiments from which he concludes that 

 there is no absorption corresponding to the emission of light by 

 a gas which is caused to radiate by an electric discharge. He 

 makes certain deductions as to the temperature of the gas which 

 emphasise the difficulty of defining " temperature " in the case 

 of a non-steady state ; but, whatever is to be deduced from his 

 observation, it certainly lends weight to the suggestion that the 

 corona is due to an emission of a similar character to that of a 

 gas transmitting an electric xlischarge. 

 April 30. Geo. Fras. FitzGerald. 



Rock-structures in the Isle of Man and in South Tyrol. 



Mr. Lami'Lugh's recent paper referred to in his letter in 

 Nature of April 26 (p. 612) is devoted to an elucidation of the 

 "relations of the Carboniferous limestone to the Carboniferous 

 volcanic rocks"' in the Isle of Man {QJ.G.S. 1900, p. 11). 

 From Mr. Lamplugh's description, these relations are very 

 similar to the relations which I described as subsisting between 

 the Mid-TrJassic dolomitic limestone ("Mendola Dolomite") 

 and the tufaceous " Wengen " beds of Enneberg. The "Buchen- 

 stein Agglomerate" of Enneberg, which I mentioned in my 

 letter (Nature, March 22), had been described in geological 

 literature as a "Middle Triassic agglomerate" of local occur- 

 rence above " Mendola Dolomite," in the neighbourhood of 

 eruptive outbursts of that age. My map and sections showed 

 that the agglomerate had a limited occurrence in fault-zones 

 and overthrust-planes where difterential movemeat had taken 

 place between the harder, more resisting •' Mendola Dolomite " 

 and the yielding, mixed "Wengen" series "comprising dust- 

 tuffs and lavas, as well as fossiliferous shales and shaly lime- 

 stones." I therefore explained the so-called "Triassic" 

 agglomerate as a subsequent structure, of the nature of a shear- 

 breccia, produced by the earth-movements of the later Alpine 

 upheaval {Q.J.G.S. 1899, pp. 567, 584, Figs, i, 4, 9, 10). 



Mr. I^amplugh descril)es in the Carboniferous series of the 



Isle of Man rock-structures of brecciated limestone, tuffs with 



tontained strips of limestone, and coarse agglomerate which had 



previously been referred to the effects of Carboniferous eruptive 



NO. 1592. VOL, 62] 



action. ' Mr. Lamplugh's explanation is that the various com- 

 plexities in the structure of these rocks " have not been caused 

 by the volcanic outburst, but have been brought about at a later 

 date' by the differential movement of segments of the eruptive 

 rocks upon their original floor of limestone" {Q.J.G.S. pp. 15, 

 19, Figs. 3, 4). The parallelism between the two cases is self- 

 evident. In 1894, I had explained on precisely the same prin- 

 ciple of subsequent differential movement, the occurrence of 

 certain anomalous phenomena at the upper limit of the Wengen- 

 Cassian series in Enneberg, i.e. the limit of this plastic and 

 compressible series against the higher horizon of Triassic calcareo- 

 dolomitic rock, termed " Schlern Dolomite" ("Coral in the 

 Dolomites," Geol. Mag. 1894, p. 55). 



The parallelism in the general sequence of events in the Isle 

 of Man and in South Tyrol is as follows : — 



Isle of Jifan. i Enneberg. 



Pre-Carboniferous Movement. Pre-Triassic Movement. 



Lower Carboniferous Deposition, j Triassic Deposition. 

 Subsequent Movement. | Subsequent Movement. 



The crust-movement immediately antecedent to Triassic de- 

 position in South Tyrol was that which accomplished the 

 upheaval of the Permian Alps, post-Triassic crust-movement 

 culminated in the upheaval of the present Alps (aut. Q.J.G.S. 

 1899, p. 628, and Nature, Sept. 7, 1899, pp. 445-6). 



The farther issues of my paper in showing how differential 

 movements twist the rocks by taking place in cross-directions 

 were not touched in my letter of March 22, for the reason that 

 Mr. Lamplugh did not in his paper enter into the torsional 

 results of differential movements. But, as I have elsewhere 

 expressed, rock-torsion or " warping " goes on all the time in 

 crust-folding, and clearly, where from any cause whatsoever 

 there is the greatest complexity in the differential movements, 

 there will be the greatest complexity in the torsional phenomena. 

 Maria M. Ogii.vie Gordon. 



POMPEII AND ITS REMAINS.^ 

 npHE city of Pompeii is one which will ever maintain 

 -*■ a hold upon the imagination of cultured man, as 

 much for what it represented in the history of civilisation, 

 as for being the victim of one of the most awful visitations 

 of the powers of nature which have ever befallen the 

 abiding place of a great society of men. It is not the 

 place here to descant upon the wealth and luxury of its 



Fig. I.— Plan of the Temple of Ms. 

 I, Portico ;"2, cella ; 3, shrine of Harpocrates ; 4, pur^atorium ; 5, hall of 

 initiation ; 6, hall of mysteries ; 7, 8, g, abodes of priests ; a, colonnade ; 

 b, refuse pit ; c, niche for statue of Bacchus ; lid, niches ; e, large altar. 



inhabitants, on the bright and reckless lives which they 

 led, on the splendour of its buildings, or even the fancied 

 security wherein men and women lulled themselves, not- 

 withstanding the violent shock of earthquake which 

 shook the city to its very foundations on February 5, 

 A.D. 63, for all these things are the commonplaces of 

 history ; but we are concerned with the remains left by 

 the awful catastrophe which took place on August 24, 



Kelsey 



Pompeii, its Life and Art 



p. xxii + 509. (New Yorl 



y August Man. Translated by F. W 

 •k : The M.ncmillan Co., 1800.) 



