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WM. GAERTNER & CO. 



Astronomical and 

 Physical Apparatus 



SPECIALTIES 



Standard Apparatus of New and Improved Designs 

 Readins Microscopes and Telescopes 



Dividing Engines 



Comparators 



General Laboratory Apparatus 



Astronomical Telescopes 



Spectroscopes 



Michelson Interferometers 



Heliostats 



5345 and 5349 Lake Ave, 



Universal Laboratory Supports 



CHICAGO 



Portabio Equatorial Telescope with 

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ELEVENTH EDITION 



THB iVlIOROSCOPEs 



fin introduction to Microscopic Methods and to Histology, by 

 Simon Henry Gage of Cornell University. The 11th edition 

 has eight pages of new matter and corrections, otherwise it is 

 like the 10th ed. Price $2.00 postpaid. 



COMSTOCK PUBLISHING CO., Ithaca, N. Y» 



Reminder to School Superintendents 



and Science Instructors ^ 



Please clip this out as a reminder to write for 

 Ohapco Purchase Guide No. 11. sent free. It il- 

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Chicago Apparatus Co. ss s. ciinion St. Chicago 



MARINE BIOLOGICAL LABORATORY 



WOODS HOLE, MASS. 

 biuiosical Material 

 L. Zoology. Preserved mavcncl of all types o{ animali 

 for class work and for the museum. 



2. Embryoloffy. Stages of some invertehrates, fishes (in- 

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 aome mammals. 



3. Botany. Preserved material of Algae, Fungi, Liver- 

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GEORQB M. GRAY, Curator, Woods Hole, Mass. 



PROVIDENT TEACHERS' AQEN«.Y 

 120 Tremont Street BOSTON, MASS. 



We enroll and we recommend teachers and officen 

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Works of Joseph P. Iddings 



Rock Minerals 



Second Edition, Revised and Enlarged 



Their Chemical and Physical Characters and their Determination in Thin Sections. 

 xiii+617 pages, 6x9, 500 figures, and 1 colored plate. Cloth, $5.00. 



Igneous Rocks 



Two Volumes 



Composition, Texture and Classification, Description and Occurrence. 



Volume I. xi+464 pages, 6x9, 130 figures, and 1 colored plate. Cloth, $5.00. 



This volume treats on the Chemical Composition, Crystallization and Texture, Modes of Occurrence, 

 and the Quantitative Classification of Igneous Rocks. 



Volume II. xi+685 pages, 6x9, 20 figures, 7 maps (6 colored), and over 2,000 chemical analyses of 

 rocks. Cloth, $6.00 net. 



Part I. of this volume deals with the Description of Igneous Rocks, and Part II. covers the Occur- 

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London: CHAPMAN & HAUL, Ltd. 



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