646 



SCIENCE. 



[N. S. Vol. XII. No. 304. 



mations of the existing continents. Mesozoic 

 and Tertiary geology are treated in the same 

 comprehensive way, in the endeavor to show 

 the former relations of sea-level to the lands. 



In the last chapter of this volume, Suess 

 gives the principal points in his theory. 

 "Once," he states, "that the marine depres- 

 sions are regarded as sunken tracts, the con- 

 tinents acquire the character of horsts, and 

 the pointed form directed towards the south, in 

 the case of Africa, India and Greenland, is ex- 

 plained by the intersection of fields of sinking 

 of which the principal domain is found in the 

 south. 



" The crust of the earth sinks ; the sea follows 

 it. But inasmuch as the sinkings of the litho- 

 sphere are limited in extent, the lowering of 

 the surface of the sea affects the entire perim- 

 eter of the oceanic areas ; it produces a gen- 

 eral negative movement. 



"The formation of sediments causes a posi- 

 tive uninterrupted eustatic displacement of the 

 shore-lines." Other causes, such as variation in 

 the quantity of water in the seas dependent 

 upon the rate of formation of silicates and 

 upon the variable action of volcanoes, give rise 

 also to eustatic movements of the ocean. 

 . These changes with the movements of the 

 ocean above noted form the outlines of his 

 theory. 



Suess appears to be placed in the necessity 

 of minimizing the changes of level which 

 many geologists have postulated in recent 

 geologic time, for these supposed changes 

 exceed the effects attributable to the operations 

 which he invokes. Thus, to take but one ex- 

 ample of evidence adduced in favor of profound 

 alteration of level — that of the so-called sub- 

 marine gorges of the Hudson, the Congo, and 

 other rivers, Suess contends with Forel and 

 others that these channels are the result 

 of excavation and deposition now going on 

 as in Lake Geneva, In this view such 

 cafions are not criteria of change of level. 

 To this criticism of the doctrine of extreme 

 changes of recent level may be added that 

 made by Davis upon the interpretation of 

 fjords in high glaciated latitudes, that the ice 

 has excavated the deep fjords and that their 

 depth below sea level is not necessarily a 



measure of depression of the land (Proc. Bos- 

 ton Soc. Nat. His., Vol. XXIX. 227-322. 

 1900). So also the high terraces reported in 

 the far north are not without close scrutiny to 

 be taken as evidence of elevation since there 

 are diverse kinds of terraces, some of them 

 built in ice-coni5ned waters far above sea-level. 



It is understood that the venerable author of 

 Das Antlitz der Erde has in preparation a con- 

 cluding section of his great work. In that we 

 may expect to find the discussion of many 

 questions, which his singularly attractive 

 hypothesis of a swinging, rising and falling 

 ocean raises, in the light of the work of Lord 

 Kelvin and other physico-geologists upon the 

 rate of contraction of the earth and upon the 

 apparent tilting of a continent with its Great 

 Lakes, as in the case of North America. 



The two volumes of the new French edition 

 form perhaps the best summary extant of the 

 geology of the globe and should find an English 

 translator. 



J. B. WOODWORTH. 



Mesures ilectrique ; essais laboraioire. By E. 



ViGNEEON and P. Letheulb. Paris, Gauth- 



ier Villars. (No date.) 

 Besistance electrique el fluidite. By Gour6 de 



ViLLEMONTE^, Paris. Gauthier- Villars. (No 



date.) 



These two small octavo volumes, of one hun- 

 dred and eighty and one hundred and eighty- 

 seven pages respectively, are installments of 

 the Eiieyclopedie sdentifique des aide-memoire. 



The first contains a good discussion of the 

 methods for measuring electric current, electro- 

 motive force, resistance, electrostatic capacity- 

 and self-induction. 



The second is a very complete resume of the 

 experimental work that has been done in the 

 attempt to discover the relationship between the 

 electrical resistance of electrolytes and their vis- 

 cosity. 



Vigneron and Letheule devote eight intro- 

 ductory pages to generaliles sur les grandeurs. 

 They say that " une grandeur est dite mesur- 

 able quand on peut la comparer a une grandeur 

 de meme espece et que le resultat de la compa- 

 raison donne k notre esprit une satisfaction com- 

 plete." This statement is, indeed, somewhat 



