574 



SCIENCE. 



[bi.S. Vol. XXIII. No. 589. 



oeciipios. First as last, it is directly 

 through ideals and indirectly through ad- 

 ministrative provisions that further ideals, 

 that the welfare of academic concerns is 

 determined. 



Joseph Jastrow. 

 TJniveesity of Wisconsin. 



SCIENTIFIC BOOKS. 



Elements of Mechanics; Forty Lessons for 

 Beginners in Engineering. By Mansfield 

 Merriman, Professor of Civil Engineering 

 in Lehigh University. New York, John 

 "Wiley and Sons. 1905. 



Elements of the Kinematics of a Point and 

 the Rational Mechanics of a Particle. By 

 G. O. James, Ph.D., Instructor in Mathe- 

 matics and Astronomy, Washington Uni- 

 versity. 



Professor Merriman believes that " there 

 should be given in every engineering college 

 two courses in rational mechanics, an elemen- 

 tary one during the freshman year in which 

 only as much mathematics is employed as is 

 indispensably necessary, and an advanced one 

 after the completion of the course in calculus." 

 The forty lessons contained in this book on 

 the ' Elements of Mechanics ' are intended to 

 cover the suggested elementary course. Its 

 seven chapters are entitled Concurrent Forces, 

 Parallel Forces, Center of Gravity, Resistance 

 and Work, Simple Machines, Gravitation and 

 Motion, Inertia and Rotation. The treatment 

 of these topics is characterized by the sim- 

 plicity of statement and illustration which 

 are familiar to users of the authoi-^s numerous 

 other text-books for students of engineering. 

 His aim seems to be to give the student work- 

 ing rules in the quickest and most direct man- 

 ner, and to this end strict logical rigor and 

 accuracy of definition and statement are some- 

 times sacrificed. 



There is no formal statement of the laws 

 of motion in their ordinaiy form, but ten 

 ' axioms ' are given which presumably are 

 designed to appeal more directly to the ex- 

 perience of the beginner. It is to be feared 

 that certain of these are stated with too little 

 care as regards accuracy (for example, ' when 



only one force acts upon a body it moves in a 

 straight line in the direction of that force '), 

 and that others will be found too vague to be 

 of much service. This vagueness is due in 

 part to the failure to give definiteness to the 

 conception of force. No student can think 

 clearly and correctly about force imtil he has 

 grasped the elementary notion that every force 

 is exerted hy one body or portion of matter 

 upon another, and that a force exerted by A 

 Upon B is always accompanied by an equal 

 and opposite force exerted by B upon A, the 

 two forces constituting the action and reac- 

 tion of Newton's third law. This funda- 

 mental principle is not expressed nor even 

 implied in the ten axioms given in this book; 

 on the contrary, the author's explanation of 

 his third axiom involves a wholly erroneous 

 statement of the law of action and .reaction. 



It is, however, .to the practically minded 

 student rather than to the stickler for logical 

 rigor that Professor Merriman addresses him- 

 self primarily, and from his point of view 

 such defects as are here criticized are of minor 

 importance in comparison with simplicity and 

 directness in the presentation of working 

 rules. With this point of view many teachers 

 bf mathematical subjects to students of engi- 

 neering will largely sympathize, and they will 

 ■ find in this book the merits which are con- 

 spicuous in the author's previous text-books. 

 Not the least of these merits is the large nura- 

 ber of examples, mostly numerical, to be solved 

 by the student. 



The book of Dr. James is designed as an 

 introductory course in rational mechanics, 

 but it is addressed not to students of engi- 

 neering but to those whose interest is in pure 

 science. It contains little of application, but 

 aims at a rigorous and thoroughly sound 

 formulation of fundamental principles. 



The treatment of kinematics," which oc- 

 cupies Part I., is clear and concise throughout. 

 This conciseness is aided by the free use of the 

 notions and language of vectors, especially 

 the notion of the geometric time-derivative in 

 the treatment of curvilinear motion. The use 

 of the term displacement to designate the 

 position-vector of a moving particle seems, 

 however, singularly inappropriate. 



