SCIENCE-ADVERTISEMENTS 



Save Middlemen's Profits on Science Apparatus when jXipp;n|j^yOpUr | 



prices which include extravagant traveling expenses and the extra profits of jobbers and dealers, ^ 



when you can send your orders direct to our factory and in all probability M 



SAVE 2S% ON SCIENTIFIC APPARATUS I 



Chapco Laboratory supplies are of the highest grade; 

 in their power to demonstrate scientific laws and principles. 

 Bire. Every Ohapco article ia guaranteed to give eatisfaction or 

 money refunded. Adjustments are always made cheerfully. Shipped 

 in dust-proof packages bearing our easy-to-check-labels which, in- 

 sure accuracy and fncility in cbecting shipment. No charge for 

 boxing, packing or cartage at this end. 



Write for ChapCO Book No. II state your school con- 

 '^ .. I nection and get a copy FREE. 



It contains a comprehensive list of articles for laboratory use. Hun- 

 dreds of articles fully described and pictured. Our prices are the same 

 to all an^ will be found the lowest possible on high grade apparatus. 



scientifically accurate and absolutely unfailing ^ 

 In the hands of students they give the results you de- ^ 



= Ohapco Scientific Apparatu 

 = trial order to test our servic 



I CHICAGO APPARATUS CO., 



55 S. Clinton St., Chicago 



lllllillllllllllllllllil 



Free Book Coupon * 



sOo. 



Chicago Apparati 



bb S. Clinton Street, Chicago, Illinois 

 Dear Sirs:— Please send your Chapco Book No. 11 to 

 my address providing I incur no obligation by your 

 compliance with this request. Our school ie interested 

 in apparatus checked in the squares below. 



D Agricultural Apparatus D Physicial Apparatus 

 D Chemical Apparatus D Biological Apparatus 



Natural History iWaterial 



ZOOLOGY MINERALOGY 



We have been handling Natural History 

 Material of all kinds for the past fifty years, 

 and so have accumulated a very complete stock. 

 Our prices are as low as the quality of the 

 speoimens will permit. We are constantly pre- 

 paring circulars and price lists covering our 

 material in the different branches, which we 

 will be pleased to send free of charge to the 

 readers of Science. 



Some of onr recent circalats : 



S-121 Rare Bird Skins 

 S-122 Mounted Bird Skins 

 S-98 Material for Dissection 

 S-123 Philippine Land SheUs 

 S-120 Special Minerals 

 S-110 Complete Trilobltes 

 S-Ul Jurassic Fossils 

 S-119 Cretaceous Fossils 



CONCHOLOGV 



GEOLOGY 



Ward's Natural Science 

 Establishment 



College Ave. Rochester, N. Y. 



Just "Published 



PRINCIPLES OF 



STRATIGRAPHY 



BY 



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



PROFESSOR OF PALAEOIMTOLOGY IN 

 COLUMBIA UNIVERSITY 



Large Octavo, 1150 pages, with 264 illustratlonB In the text. 

 Cloth bound, price, $7.50. 



Bend for descriptive circular 



A G. SEILER & CO. 



PUBLISHERS 

 1224 Amiterdam Avenue ^EW YORK. N. Y. 



