LITERARY NOTICES, 



847 



and alertness. At home as well as at 

 school, children should be taught to 

 think the thoughts that are suited to 

 their age and capacity ; and the neglect 

 of such thought as is quite within their 

 powers should be treated as a fault. 

 "We are confident that when a general 

 effort comes to be made for the specific 

 purpose of awakening intelligence, and 

 when, for tlie furtherance of this end, 

 we throw away a great quantity of the 

 useless lumber with which we now en- 

 cumber the minds of the young, the re- 

 sult will be a great development of good 

 sense and practical efficiency. 



LITERARY NOTICES. 



A Text-Book of General Astronomy for 

 Colleges and Scientific Schools. By 

 Charles A. Young, Ph. D., LL. D. Bos- 

 ton: Ginn & Co., 1888. Pp. 650. Price, 

 12.40. 



Prof. C. A. Young's " Text-Book of Gen- 

 eral Astronomy for Colleges and Scientific 

 Schools " is a work worthy of the reputation 

 of its author, and creditable to the progress 

 of American science. Not only his long ex- 

 perience as a teacher is manifested in the 

 book, but also the character of his teaching, 

 which is clearly that of a man in close sym- 

 pathy with his students, who perceives accu- 

 rately the attitude of their minds toward the 

 subject, and knows just when and where to 

 lend assistance. It is no mere compilation, 

 but, to an uncommon extent, an original 

 work. In some text -books of astronomy 

 many things that the really earnest student 

 wants to know seem to have been carefully 

 excluded ; he gets results, but not the meth- 

 ods of attaining them, and he can not help 

 feeling that the author has kept him out of the 

 secret, as if it were a performance in presti- 

 digitation. Prof. Young's book is admirably 

 free from this fault. He not only explains 

 principles and methods with unusual dis- 

 tinctness, but he is careful to show the stu- 

 dent where to go for further or fuller infor- 

 mation. And when he sends the beginner 

 to higher works he starts him off with a clear 

 conception of what he is to go for, which in 

 itself is half the battle. Moreover, he takes 

 pains to point out the limitations of the sci- 

 ence — a thing of greater importance than 



may at first sight appear. For instance, 

 what he says of the nature of the attraction 

 of gravitation is something that the ordinary 

 student rarely gets, but that is of the first 

 importance for a proper comprehension of 

 the subject : " We must not imagine the 

 word ' attract ' to mean too much. It merely 

 states the fact that there is a tendency for 

 the bodies to move toward each other, with- 

 out including or implying any explanation 

 of the fact. So far no explanation has ap- 

 peared which is less difficult to comprehend 

 than the fact itself. Whether bodies are 

 drawn together by some outside action, or 

 pushed together, or whether they themselves 

 can act across space with mathematical in- 

 telligence — in what way it is that ' attrac- 

 tion ' comes about is still unknown — appar- 

 ently as inscrutable as the very nature and 

 constitution of an atom of matter itself ; it 

 is simply a fu7idamc7ital facf" {p. 109). 



The whole tone of the book is stimulating 

 and suggestive. It is interesting to the gen- 

 eral reader as well as to the student. The 

 chapter on " The Earth as an Astronomical 

 Body," for instance, is a beautiful example 

 of comprehensive treatment combined with 

 clear and succinct statement, including, with 

 an explanation of just those principles that 

 the student needs to have made plain, a 

 summary of the latest knowledge which in- 

 terests everybody. To particularize a little, 

 we have not seen in any work of the kind so 

 perspicuous and satisfactory an account of 

 the Foucault experiments with the pendulum 

 and the gyroscope as that given by Prof. 

 Young. 



Among the little things, which are too 

 often entirely overlooked by writers of text- 

 books, but whose suggestivcness and value in 

 awakening the interest of the student, and 

 clarifying his ideas, have been recognized in 

 this book, we note the demonstration of the 

 eastward deviation of falling bodies (p. 94) ; 

 the explanation of how the height of the 

 mountains of the moon is measured (p. IIQ) ; 

 the ingenious proof of the moon's rotation (p. 

 154); and the stimulating little example on 

 page 123, showing how the eccentricity of 

 the earth's orbit may be found from the 

 greatest and least apparent diameters of 

 the sun. 



As was to be expected from the author's 

 wide reputation and recognized authority as 



