Sixth Year. 

 Vol. XI. No. 276. 



SCIENC 



NEW YORK, MAY iS, li 



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An AgriciiUural Survey of the United States. — Tlie Interna- 

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 The Agricultural Value of the Mackenzie Region. 



Economy of Food ..... 

 Exploration of the Obangi- Welle 

 Scientific News in Washington. 



The Work of the ' Grampus ' . . . 



Dictionary of Nortli American Indian Tribes 

 Reclamation of Arid Lands .... 



Re-organization of the United States Fish Commission 



Health Matters. 



Contagion in Courts ..... 



Educating the White Blood-Corpuscles 



Electrical Science. 



Sir William Thomson's Electrical Measuring-Instruments 



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237 

 237 



Elongation and Contraction of Metals in Magnetic Fields 



A New Alternating-Current Electro-Motor . 



Heating Effect of Electric Currents 



Variation of Co-efficients of Induction 



New Method of reading Reflecting-Instruments 



Book-Reviews 



Tenth Annual Report of the Connecticut State Board of Health 

 Eleventh Annual Report of the Board of Health of the State of 



New Jersey .... 



Evolution and its. Relation to Religious Thought 

 Accidents and Emergencies 

 Practical Education 



Notes and News 

 Letters to the Editor. 



Is the Rainfall increasing on the Plains? 

 Disparate Vision . , 



Agriculture and Late Quaternary Geology 

 Queries and Answers 



A. W. Greely 



W. LeConte Stevens 



. E. W.Hilgard 



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BOWSER'S MATim-MATICAL SERIES 





T^W^O 



Will be Publisn^:: '^fK'^^^^^,J^■^rv% ist, 

 COLLEGE ALGEBRA. 



12mo, 550 Pages, . - . . - Price, $2.00 



This work is designed as a text-book for Academies, Colleges, and Scientific Schools. It begins at the beginning of the subject, and the full 

 treatment of the earlier parts render^; it unnecessary that students who use it shall have previously studied a more elementary Algebra. 



When a student goes from Algebra to higher branches, it is ofien found that much which he should have studied in Algebra has been either 

 not learnt at all, or so imperfectly learnt as to require the ground 10 be all gone over again. It is h iped that students who use this book, under the 

 direction of a good teacher, will be able to so master the elements of Algebra that they may rise from it to more advanced mathema'ics, not only 

 without having anything to unlearn, but with a good foundation. While very much depends upon a good text-book, the author believes that no 

 kind of instruciion in mathematics can take the place of that given by the living teacher. No subject requires so much individual attention, or 

 such close intellectual contact between instructor and pupil. fhe teacher must not be satisfied even with the learner's statement that he under- 

 stands the point presented. He must by persistent questioning assure himself that the idea has been thoroughly grasped and mastered. 



Nothing is more pleasing to a young student than to see and feel that he can use his knowledge to some practical end. For this reason the 

 author has introduced a chapter on easy equations and problems before the chapters on Factoring and Fractions ; this enables the student early to 

 become acquainted with some of the most interesting practical applications of the subject. 



A good deal of stress is laid on solving quadratic and other eq ations by means of factors which are often obvious on inspection. In an im- 

 mense number of cases this is a much easier way than by completing the square, and besides it gives an insight into the nature of equations. The 

 student's first thought, on looking at an equation, should be : can it ht resolved into fictors ? If it can, his work is done ; but if he is not able 

 readily to see the factors, he has still left the old method of completing the square. 



The examples aic very numerous. Each set is carefully graded, beginning with those which are very easy, and proceeding to others which 

 are more difficult. The large number of examples is givsn for tne convenience of the instructor, that he may have, year by year, a sufficient variety 

 from which to select, to prevent mere rote-work on the part of his pupds. Every teacher knows that the note-books with solutions of difficult ex- 

 amples are handed down from one class of students to another, till a sort of key is formed, often to the destruction of intellectual discipline. 



ACADEMIC ALGEBRA. 



12mo, 350 Pages, Price, $1.50. 



(This work is designed as a text-book for Common and High Schools and Academies, and to prepare students for entering Colleges and 

 Scientific Schools. (The book is a complete treatise on Algebra up to and through the Progressions, containing thus far precisely the same subjects 

 and the same treatment of them ihat are found in the College ."Algebra.) For students Avho have not sufficient time to take the College Algebra, 

 this perhaps is the better book ; bitt those who contemplate entering College, or who wish to lake a complete course in Algebra, may as well begin 

 at once with the larger work,) 



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