SCIENTIFIC LITERATURE. 705 



improvement of which has hardly begun, and which offer a promising field 

 for experiment — the persimmon, pawpaw, whortleberry, buffalo berry, 

 barberry, and nuts. The whole history of the improvement of American 

 fruit is interpreted by Professor Bailey as showing that in nearly every case 

 the amelioration has come from the force of circumstances, and not from 

 the choice or design of man, principally because foreign species did not do 

 well and something adapted to American conditions had to be found. Yet 

 much skill has been shown in recognizing the good qualities of the native 

 species, and in giving them conditions favorable to improvement. For the 

 future the author believes that the best results at the amelioration of any 

 species are to be expected by workiug with the highly improved forms 

 rather than with the original wild stock. We need, he says, a greater 

 range of variation, more divergent and widely unlike varieties, and more 

 incidental or minor strains of the most popular and cosmopolitan sorts. 

 Professor Bailey finds the greatest satisfaction in his book in the record of 

 the men who have been instrumental in introducing the improved fruits. 

 No men have been greater benefactors to our country than these, who have 

 done the equivalent of making two blades of grass grow where only one 

 grew before, and have added to the healthful sum of pleasure and content. 



As Professor Darwin truly says, a mathematical argument is, after all, 

 only organized common sense; but, unfortunately, it is usually in such a 

 highly organized form as to be beyond the intelligence of the average 

 reader. In the present volume,* however, the author has wonderfully 

 simplified a most intricate and difficult mathematical subject, and really 

 seems to give some justification for the above generalization. 



The first chapter of The Tides is devoted to defining them and describ- 

 ing methods of observation and study. The curious tidal movements in 

 lakes, called seiches, which were first systematically studied by Professor 

 Forel on the Lake of Geneva, are taken up in the second chapter ; an 

 account of Forei's work is given, and the statement made that similar 

 researches are now under way on other lakes, notably that of Mr. Denison 

 on Lake Huron in this country. Tides in rivers, including an account of 

 the curious tidal phenomenon known as a " bore," are next described, the 

 laws governing their variation and the ways in which they differ from the 

 tides of the open sea being carefully laid down. A brief historical chapter, 

 containing some curious extracts from Chinese and Icelandic literature, is 

 rather instructive anthropologically than tidally. The three following 

 sections are taken up by a study of tide generating and modifying forces, 

 and include an interesting account of the experiments made some years 

 ago by Dr. Darwin and his brother, in an effort to measure tidal forces by 

 means of the bifilar pendulum, which is now such an important agent in 

 seismological investigation. Chapters IX and X give an account of the 

 equilibrium, and the dynamical theories of the tide-generating forces, and 

 are chiefly accounts of the devices by which mathematicians have endeav- 

 ored to bring artificial order out of the actual chaos. The great complexity 

 of this portion of the subject; the variety of forces operating to produce 

 the tides, the sun, the moon, the earth's rotation, etc. ; and the number of 

 retarding and confusing elements, friction, interposed land masses, river 



* The Tides; and Kindred Phenomena in the Solar System. The Lowell Institute Lectures for 

 1898. By George Howard Darwin. N:w York : Houghton, Mifflin & Co. Pp. 378. $2. 

 VOL. LIV. — 53 



