IS*? 



NA TURE 



[April 8, 190Q 



The omission of certain branches of the subject called 

 for comment, because it is precisely these which, as a rule, 

 are not adequately treated in English text-books. The 

 ordinary text-books are out of date, and I cannot but 

 think an excellent opportunity of supplementing their 

 belated information has been missed. It would not prove 

 a very easy task, however. 



The map on Plate XVI. was criticised independently of 

 the letterpress, because a map should speak for itself, and 

 in some detail, because it represents that part of the world 

 most familiar to us. I must confess that the more I study 

 this map the less I like it. I do not know why the 

 Guadalquivir fault is more " essential " than many other 

 features of Spain, and the true form of the Meseta, which 

 it helps to define, would have been better shown if the 

 dislocation which forms the eastern boundary of the 

 Meseta had been introduced. The " grain " of the land, 

 shown by heavy blue lines like those used to express 

 the Caledonian trend in Scotland, and not black like the 

 Armorican in Brittany, is not correctly given even by 

 those lines which are cut off by the fault ; if they had been 

 more precisely indicated and the Asturian curves added, a 

 definite system, somewhat resembling a nest of parabolas, 

 would have made itself manifest. The fundamental struc- 

 ture of the Meseta would then have been visible at a 

 glance. Had only as much of these lines been intro- 

 duced as is required to show their relation to the fault, 

 the only objection that could have been raised would 

 have been as to their incompleteness ; as it stands, my 

 comment that the map fails to express the true structure 

 of Spain is a mild way of stating the facts. Passing to 

 the Armorican peninsula, which, thanks to the observa- 

 tions of Barrois, is better known, we again find the trend 

 lines out of drawing. It is difficult to know on what 

 principle some have been omitted and others introduced; 

 the omission does not make for clearness, and in this 

 case, as in that of Spain, a truthful rendering would have 

 simplified the facts by making them more intelligible. If 

 the lines of Armorica had been properly generalised, we 

 should have seen one of the most important of them {axe 

 de Cornouaillcs) pointing straight at the Central Plateau, 

 and the introduction of trend lines in the Central Plateau 

 would have made clear the relation on which I insisted 

 when pointing out that the connection of the trend lines 

 of Brittany and the Central Plateau is no hypothesis, but 

 a definitely known fact. 



As it stands on the map, I still think the legend 

 " Archaean Plateau of North-Western Europe " written 

 across a tract showing strong Caledonian folding is con- 

 fusing, and I cannot agree that anything in the subsequent 

 history of this Central Plateau or of Spain calls for its 

 distinction by colour from the rest of the Hercynian system ; 

 I am the more disposed to object to this colour scheme, 

 since the same colour is used for Spain, the Central 

 Plateau, and the so-called Archjean Plateau of the north, 

 thus introducing a second source of confusion. It was not 

 complained that the structure of Asia Minor is omitted 

 from the map which bears the title " Europe," but that 

 an important line common to Europe and Asia is wrongly 

 drawn. The Cyprus-Taurus line is one of the most con- 

 spicuous on the map, and is rendered all the more so by 

 the omission of other lines in Asia Minor. That part of 

 it (in Transcaucasia) which is most erroneously drawn is 

 not dotted in, but continuous; but even in Europe it does 

 not run true, the relation of the Peloponnesus to Crete 

 being inexactly indicated. In the map of Asia greater 

 care is exercised over this and related lines, but if Oswald's 

 account of Armenia is correct there is still room for 

 improvement. I am unaware of the existence of a moun- 

 tain " knot " south of the Caucasus. 



The objection to the diagram section shown in Fig. 83 

 is that the vertical scale is somewhere between 50 and 100 

 times the horizontal. Geologists have long agreed that 

 such exaggerations are to be deprecated. 



Assuming that the Eskimo are modified Mongolians, 

 how does the action of the environment, as asserted by 

 the author, account for the chief modification which dis- 

 tinguishes them, that is, the elongation of their heads? 

 and to this I may add now the length of their face and 

 the narrowness of their nose. The question involved 



NO. 2058, vol: 80] 



is the direct action of the environment, and in my 

 opinion schoolboys should not be indoctrinated with 

 notions of this kind. Again, admitting that the 

 Australian aborigines are related to what the author calls 

 " Caucasians," what reason is there for the assertion that 

 they are " modified Caucasians "? This is to invert the 

 order of facts. Numerous important anatomical characters 

 stamp these people as a primitive race. The most 

 plausible speculation would assign them a position near 

 the root of the " Caucasian " stem, regarding them as an 

 unprogressive survival of an ancestral stock rather than 

 as one of the higher races " modified by adaptation to 

 life in an arid region." But why introduce these jejune 

 speculations at all? 



The real gravamen of the criticism to which objection 

 is taken lies in the remark that the author has not been 

 sufficiently careful to distinguish between opinion and fact. 

 The treatment of the whole question of the form of the 

 earth is open to this charge. I do not understand the 

 cryptic remark which the author interjects in his refer- 

 ence to this matter, but I may add that, in the opinion of 

 competent mathematicians, there is no sound physics or 

 dynamics at the back of the " tetrahedra! " theory. It 

 has proved wholly unfruitful, and has made no real scien- 

 tific progress. That it has grown in popular favour is 

 probably true, and its dogmatic presentation in a school 

 text-book is calculated to advance it still further in this 

 kind of progress ; I cannot believe that this will be wholly 

 to the satisfaction of the author, since I credit him with 

 a juster appreciation of the responsibility which attaches 

 to the instruction of vouth. The Reviewer. 



The Gases of the Ring Nebula m Lyra. 



Every friend of astronomical research has learned with 

 great pleasure the news that Prof. Wolf, of Heidelberg, 

 has succeeded in proving by spectrum photography that the 

 well-known ring nebula in Lyra consists of four different 

 gases, which, owing to the rapid rotation of the ring, have 

 been separated and concentrated in four different layers. 

 On using the image of the ring itself instead of the slit 

 of a spectroscope, photographic images of the rings corre- 

 sponding to the different spectral lines were obtained on 

 the plates, but the dimensions of the rings were found to 

 be different and to correspond to four gases of which the 

 ring nebula is composed. The smallest ring. A, repre- 

 senting the innermost part of the ring, is composed of an 

 unknown gas ; the next largest ring, B, is composed of 

 hydrogen ; the next largest ring, C, consists of helium ; 

 and the largest ring, D, consists of an unknown gas. 

 The question arises, What is the nature of the two un- 

 known gases? 



Bredig found in 1895 that if a mixture of two gases is 

 subjected to centrifugal rotation, the relative concentration 

 of the gas of higher molecular weight (i.e. higher density) 

 increases with the radius of rotation. We must, there- 

 fore, assume that in the series of our four gases A, B, C, 

 and D, the density or molecular weight increases from 

 the smallest value of A to the largest value of D, and 

 this is, indeed, proved by the fact, found by Wolf, that the 

 gas B consists of hydrogen, molecular weight = 2-oi6, and 

 the gas C of helium, molecular weight = 3-96. From this 

 it follows that the gas concentrated in the smallest zone 

 of the ring A must have a smaller molecular weight than 

 hydrogen. This gas has not yet been isolated upon our 

 earth, but its existence and atomic weight were predicted 

 by the great Russian chemist and natural philosopher 

 Mendel^eff in a popular article published in Russian in 

 1902, the essential part of which was translated into 

 English in 1904 under the title " An Attempt towards a 

 Chemical Conception of the /Ether." 



Mendel^eff shows that if the elements of the rare or 

 inactive gases He, Ne, Ar, Kr, and Xe, discovered by 

 Rayleigh, Ramsay, and Travers, are placed in the well- 

 known nought-group, we must expect the existence of 

 elements of the same group possessing smaller atomic 

 weights than helium and hydrogen. Mendel^eff assumes 

 that in the first horizontal series of the system, on the 

 left side of, or before, hydrogen in the nought-group, where 



