Apeil 9, 1909] 



SCIENCE 



579 



men, towards the large cities and away from 

 tlie small towns and farms. This change is 

 in process at present, and must have been 

 going on for some time. Thus there is every 

 reason to suppose that by the year 1860 (if not 

 very much earlier than this) there had al- 

 ready taken place a part at least of thisi same 

 phenomenon. So that the distribution of 

 talent was then somewhat as it is to-day, con- 

 centrated about the cities.* Now if mental 

 traits are inherited,, the cities must show a 

 higher proportionate birth of talent than the 

 country, and our observed facts are only what 

 we might expect. 



Of course it is impossible here to separate 

 the question of environment, which may be 

 more favorable in the city, as some contend, 

 or less favorable, as others sometimes think, or 

 be the slight and almost unmeasurable force- 

 which I, myseH, shall be content to hold it, 

 until some one has succeeded in measuring it. 



Mental heredity, on the other hand, has been 

 measured, and the results are in substantial 

 agreement.^ 



It is' not the purpose of the present com- 

 munication to present these figures' from 

 " Who's Who " as a proof of heredity, but only 

 to point out that there is nothing in the dis- 

 tribution of the birthplaces of leading Amer- 

 icans to conflict with the strongest belief in 

 the force of inheritance, should one happen to 

 have gained such a belief from other sources. 

 Frederick Adams Woods 



Bbookune, Mass., 

 February 20, 1909 



^Oonf. J. McK. Cattell, "A Statistical Study 

 of American Men of Science," III., Science, N. S., 

 Vol. XXIV., No. 623, December 7, 1906. A. Odin, 

 " Gen6se des grands hommes," 2 vols., 1895. 



^ Conf . P. Galton, " Natural Inheritance," Lon- 

 don, 1889. K. Pearson, " On the Inheritance of 

 Mental and Moral Qualities in Man, and its Com- 

 parison with the Inheritance of Physical Char- 

 acters," Biometrica, Vol. III., 1904. E. L. Thorn- 

 dike, "Measurements of Twins," Arch, of Philos- 

 ophy, Psychology and Scientific Methods, No. 1, 

 September, 1905. F. A. Woods, "Mental and 

 Moral Heredity in Royalty," Popular Science 

 Monthly, August, 1902, to April, 1903. Same 

 with additions and further measurements. New 

 York, 1906. 



SCIENTIFIC BOOKS 

 The Principles of Mechanics for Students of 

 Physics and Engineering. By Henry 

 Crew, Professor of Physics in Northwest- 

 ern University. 8vo, 295 pp. New York, 

 Longmans, Green & Company. 1908. 

 This book represents a course which Pro- 

 fessor Crew has given for several years at 

 Northwestern University to students intend- 

 ing to specialize in physics and in engineer- 

 ing. The students have had a class and lab- 

 oratory college course in general physics and 

 more or less work in elementary calculus. 

 Professor Crew states in the preface that his 

 purpose is "to lead the student to clear dy- 

 namical views in the shortest possible time 

 without sacrificing him upon the altar of 

 logic, yet pursuing a route which he can after- 

 wards follow with safety." The plan is to 

 confine the treatment " to that part of me- 

 chanics which is common ground for the 

 physicist and the engineer" (again quoting 

 the preface). The general dynamical prin- 

 ciples involving advanced calculus and analy- 

 sis are accordingly not included. There are 

 six chapters> one on kinematics, two on kinet- 

 ics, one on friction, one on elasticity and a 

 short chapter on fluid motion. As the title 

 of the book indicates, the principles are em- 

 phasized rather than the applications. In 

 making such a book, every one will, of course, 

 have his own ideas as to topics to be included 

 and those to be omitted. Professor Crew's 

 book represents a course of the essentials, 

 which has been selected after actual class- 

 room experience. An excellent feature is the 

 attention given to rotational dynamics, a part 

 of mechanics on which many text-books are 

 weak. The " illustrative problems " and 

 " examples for practise " scattered through 

 the book are very simple, avoiding involved 

 analyses and calculations. 



While the book is intended both for stu- 

 dents of physics and of engineering, we be- 

 lieve it will appeal more strongly to the stu- 

 dent of physics and this is not so much in 

 its subject-matter as in ite temper. For the 

 general student, the purpose of the book is 

 admirable — namely, to take the student in the 



