11 



SCIENCE-ADVERTISEMENTS 



Every Teacher of Science 

 wants his work 



To develop the pupil's power to 

 observe natural phenomena. 



To arouse his permanent interest 



in science. 



To train him to observe with 



accuracy. 



To furnish him with useful infor- 

 mation. 



To prepare the way for the study 

 of special sciences. 



CLARK'S INTRODUCTION TO 

 SCIENCE 



Accomplishes These Results 

 PRICE, $1.20 



AMERICAN BOOK COMPANY 



New York Cincinnati Chicago 



Three Qualitatives 



The requirements of nearly every teacher 

 can be met by one of these excellent books. 



Dennis and WWttelsey: Quali- 

 tative Analysis. 



At the same time exact and complete. 

 The student's interest and intelligence 

 are stimulated. $1.00. 



BIcGresrory: A Iflanual of Quali- 

 tative Analysis. 



A short treatise which yet insists on 

 logical and orderly progress on the 

 student's part. $1.00. 



Sellers: Treatise on Qualitative 

 Cbemical Analysis. 



Practical, progressive, up-to-date; lays 

 emphasis on the scientific and pedagog- 

 ical aspects. Sl.OO. 



Are vou familiar with these three booJcs ? 



Ginn and Company- 



Natural History Material 



ZOOLOQY 



MINERALOQY 



We have been handling Natural History 

 Material of all kinds (or the past fifty years, 

 and so have aoonmalated a very complete stock. 

 Our prices are as low as the quality of the 

 specimens will permit. We are constantly pre- 

 paring oiroulars and price lists covering oui 

 material in the different branches, which we 

 will be pleased to send free of charge to the 

 readers of Science. 



Some of oar reoent circalars : 



S-121 Rare Bird Skins 

 S-122 Mounted Bird Skins 

 S-98 Material for Dissection 

 S-123 Philippine Land Sbeils 

 S-120 Special Minerals 

 S-110 Complete TrUoblteg 

 S-Ill Jurassic Fossils 

 S-U9 Cretaceous FossUt 



CONCHOLOQY 



QEOLOQY 



Ward's Natural Science 

 Establishment 



College Ave. Rochester, N. Y. 



Send for descriptive circulars and sample 

 pages 



PRINCIPLES OF 



STRATIGRAPHY 



BY 



AMADEUS W. GRABAU, S.M.. S.D. 



PROFESSOR OF PALAEONTOLOGY IN 

 COLUMBIA UNIVERSITY 



Large Octavo, 1150 pages, with 254 illustrations in flie text. 

 Cloth bound, price, &7.50. 



Send for descriptive circular 



A. G. SEILER & CO. 



PUBUSHFRS 

 1224 Amsterdam Avenue NEW YORK. N. Y. 



