NATURE 



91 



THURSDAY, MARCH 25, 1909. 



TIDAL RESEARCHES. 

 Manual of Tides. Part V., Currents, Shallow-water 

 Tides, Meteorological Tides, and Miscellaneous 

 Matters. By RoUin A. Harris. Appendix No. 6 : 

 Report for 1907 of U.S. Coast and Geodetic Survey. 

 Pp. 231-545. (Washington : Government Printing 

 Office, 1908.) 



THE author is to be congratulated on having 

 brought to completion in the present volume 

 a full and exhaustive study of existing- knowledge 

 relating to tides and tidal phenomena, previous in- 

 stalments of which have appeared in similar form 

 from time to time since 1894. The subject-matter 

 dealt with is of a miscellaneous character, sum- 

 marising those parts of the subject which could not 

 be previously introduced without undue diversions. 



The early chapters deal with the nature of the 

 horizontal flow in steady streams or pipes, and seek 

 to establish simple laws governing the action of fric- 

 tion in such streams. Various formulae are derived 

 or quoted which appear to accord well with the 

 results of observation, and in which for the most part 

 the action of the cross-eddies set up is found to be 

 well represented by a term proportional to the square 

 of the velocity of flow of the main current. 



In applying these results to tidal phenomena, doubt- 

 less the direct action of viscosity is insignificant, and 

 it is through the medium of such cross-eddies that 

 friction is chiefly effective. If, however, this is the 

 case, it would appear that the sensible effects of 

 friction in modifying ocean tides would be localised 

 in those regions where the configuration of the land 

 or of the ocean bed gives rise to a magnification of 

 the tidal flow large enough to be accompanied by 

 such eddies, and that the principal phenomena of the 

 tides in the open ocean will suffer practically no dis- 

 turbance from frictional causes other than those which 

 may be attributed to pure viscosity. We are thus 

 unable to accept the author's conclusion, arrived at 

 in the second chapter, as to the paramount effects 

 of friction in determining the phases of ocean tides, 

 a conclusion based on wholly unwarranted assump- 

 tions as to the quantitative effects of friction {e.g. 

 " Suppose fi' = i," p. 281), and, further, on an almost 

 complete disregard of its laws of action as exempli- 

 fied in the preceding chapter. The author, in fact, 

 reverts to the analogue of the simple pendulum subject 

 to purely viscous dissipation. 



The conclusions, as we have elsewhere pointed 

 out, are of vital importance ' for the establishment 

 of a theory of the tides put forward by the author 

 in previous volumes which has not proved acceptable' 

 to ourselves, and, in our opinion, has vitiated much 

 of the otherwise excellent work presented. For- 

 tunately, the influence of this defective theory does 

 not appear to extend further into the present volume, 

 which contains much for which students of the tides. 



1 Nature, vol. Ixxiii., p. 24f 

 the case of the tides the conditions 

 factor exist, but this contention h 

 author, and we are of opinion that 



it may be contended that in 

 render friction the controlling 



here put forward explicitly by the 



lid not be substantiated." 



whether from a practical or a theoretical aspect, will 

 be grateful. 



In the theory of river tides the author follows 

 Airy's treatment, which, while admittedly inadequate, 

 serves to elucidate some of the more pronounced 

 phenomena indicated by observation, and draws in- 

 teresting conclusions with regard to the form and 

 dimensions of estuaries. 



The chapters relating to the distribution of tidal 

 currents in various phases throughout the world con- 

 stitute perhaps the most important contribution con- 

 tained in the present volume. Besides giving a com- 

 prehensive summary, amply illustrated by diagrams, 

 from all available records, the author has included 

 much material dependent on observational data 

 specially worked up for the present publication. 



Among other matters dealt with, we may refer to 

 the subject of seiche oscillations in lakes, the general 

 circulatory system of the ocean, and many matters 

 which will prove of interest to marine engineers. 



In relation to a work where so much is praise- 

 worthy, it is with reluctance that we have felt it 

 again necessary to emphasise these points on which 

 we differ from the author. Were the work addressed 

 to mathematicians alone, this would not have been 

 considered necessary, but a word of warning seems 

 to be desirable to a large class of readers to whom 

 it will appeal who, without following out the intri- 

 cate mathematics involved, might otherwise be dis- 

 posed to accept the results as authoritative. The work 

 as a whole can scarcely fail to stimulate further re- 

 searches into the more recondite problems connected 

 with tidal phenomena. . S. S. H. 



NO. 2056, VOL. So] 



THE MORPHOLOGY OF ASIA. 

 The Face of the Earth. Vol. iii. By E. Suess. 

 Translated by H. B. C. Sollas. Pp. vii-(-40o; 7 

 plates, 23 figures. (Oxford : Clarendon Press, 1908.) 



THE Oxford translation of the third volume of 

 Suess 's great geomorphology will be welcomed 

 as warmly as its predecessors, though this part of 

 his work is perhaps of less educational value and 

 a smaller proportion of it interesting to general 

 readers. Most of this volume is occupied by a 

 detailed account of the stratigraphy of central and 

 northern Asia. Much of the literature is so in- 

 accessible that Prof. Suess 's summary of the 

 researches of the Russian surveyors will be of perma- 

 nent value as a work of reference, and as he 

 interprets and correlates the facts with his usual 

 genius, the work is of the highest value as an 

 original contribution to the tectonic geology of Asia. 

 It is accompanied by a most valuable map of the 

 structural geography of Central Asia. 



The main thesis of this volume is Suess's state- 

 ment of the essential structure of Asia and of its 

 relations to Europe. He maintains the fundamental 

 unity of Eurasia, and shows that it has been built 

 up, around, or upon a vast sheet of ancient rocks, 

 which form the Russian platform of Poland and 

 south-western Russia, and most of Scotland and 

 Scandinavia ; the old rocks are buried beneath recent 



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