SCIENCE-ADVERTISEMENTS 



What They Say 



About 



Clark's Introduction 

 To Science 



" Concrete and comprehensive." — 



" The most readable, the most teach- 

 able and the best book of its kind." — 



" Touches the practical side of life at 

 more points than any other text." — 



"Practical and up-to-date; easily 

 understood." — 



" Of much value to the student whose 

 school life ends in the high school." — 



Price, $1.20 



American Book Company 



New York Cincinnati Chicago 



Handy Manuals 



for the 



Agricultural 

 Laboratory 



To supplement outdoor work in agriculture tiie 

 two books below are exceptional in stimulating 

 close and intelligent observation. 



Laboratory Manual of Horticulture 



By George W. Hood, As- tested exercises on 



sociate Professor of Horti- seeding, seed-testing, 



culture, University of principal methods of 



Nebraska. 234 pages, il- gSfirg^'TJTSf: 



lustrated, li.oo. ing. 



Agricultural Laboratory Manual : Soils 



By Edward Scott Sell, 

 Professor of Agriculture in 

 the State Normal School, 

 Athens, Ga. 40 experi- 

 ments in loose-leaf form, 

 with heavy paper cover, 35 

 cents. 



Inquiries promptly answered 



Ginn and Company gSfJ^^/'Lldt 



Based on easily avail- 

 able material these 

 exercises cover soil 

 moisture, soil tem- 

 perature, fertilizers, 

 bacteria and tillage. 

 The manual is as well 

 adapted for use in one 

 part of the country as 

 in another. ^ 



FUNDAMENTAL SOURCES 



OF 



EFFICIENCY 



By FLETCHER DURELL, Ph.D. 



Evolution has been the leading idea during the past half century. Efficiency will 

 be the Master Idea for the next fifty years. This fact will do much to shape and 

 to aid scientific activity. 



' ' To many it came as a shock to hear that the great Mach laid stress on the 

 economy of thought in Science. . . . But in this book the studj^ of almost every 

 conceivable kind of activity, including scientific activity, is made from the abstract 

 point of view of efficiency. . . The book contains very much valuable illustrative 

 material." — Nature, London, England 



' ' The book not only invites but compels hard study and will repay it. ' ' 



— Educational Review 



"The most comprehensive and the most practical discussion of the subject 

 that has thus far been published." — ^Boston Living Age 



Send for circulars and other information to the publishers 



J. B. LIPPINCOTT CO., 



PHILADELPHIA, PA. 



