364 GEOGRAPHIC LITERATURE 



to Commissioner Chamberlain's "all others," which includes a tonnage 

 of 541,988 in canal-boats and barges; so that the figures should read, 

 steam tonnage 2,371,923, sailing tonnage 1,835,827. 



It is especially deplorable that the several errors should lie in a single 

 direction — a direction supporting argument against the Nicaragua Canal. 



W J McGee. 



GEOGRAPHIC LITERATURE 



The Tides and Kindred Phenomena in the Solar System. By George How- 

 ard Darwin. Boston and New York : Houghton, Mifflin & Co. 

 1898. Pp. xviii + 378. 



Professor Darwin is the son of the great naturalist and himself a dis- 

 tinguished mathematician. In the present volume he appears as the 

 mathematician explaining in every-day speech a subject that has else- 

 where no such treatment in our language. In this role he is as success- 

 ful as he seems to be diffident. Despite the disadvantage of the lecture 

 form, the book is extremely readable and interesting. Any one who has 

 looked through the non-mathematical literature of tides is familiar, with 

 the crude explanations found in encyclopedias and hand-books of astron- 

 omy and geography, where the moon is made to lift the ocean on the 

 side of the earth next her away from the earth, while also lifting the 

 earth away from the ocean on the further side— a statement true in a 

 way, but quite unintelligible until amplified. To such the present vol- 

 ume will prove most welcome. 



Professor Darwin gives admirably lucid accounts of the equilibrium 

 and dynamic theories, besides pointing out cleaily the failure of mathe- 

 matics to grasp the whole problem of the actual tides. The book con- 

 tains certain general tidal information, an exposition of the mathematical 

 theory, analysis and prediction of oceanic tides, and an excellent account 

 of tidal friction as an element in cosmogony. Forel's unique unmathemat- 

 ical work on the seiches of Lake Geneva receives a merited tribute and 

 its first presentation in English. 



Tides in rivers is the somewhat broad title to the account of bores/ A 

 gem of simple comprehensive statement is one of the several views of 

 tide-raising forces : " If every particle of the earth and of the ocean were 

 acted on by equal and parallel forces, the whole system would move to- 

 gether and the ocean would not be displaced relatively to the earth ; 

 we should say that the ocean was at rest. If the forces were not quite 

 equal and not quite parallel, there would be a slight residual effect tend- 

 ing to make the ocean move relatively to the solid earth. In other 

 words, any defect from equality and parallelism in the forces would 

 cause the ocean to move on the earth's surface" (p. 104). The whole 

 treatment of the tide-raising forces in both theories is very successful. 

 Use is made of W. M. Davis' suggestion of absolute equality of centrifu- 

 gal forces in every part of the earth. As gravitation varies with the 

 square of the distance, residuals of excess and defect appear which are 

 the tide-raising forces. This presentation Professor Darwin illustrates 



