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SCIENCE.— ADVERTISEMENTS. 



JULIEN'S IMPROVED LAPIDARY LATHES 



For SLICING and POLISHING rocks, minerals, fossils, 

 etc., and for GRINDING DOWN the same into micro- 

 scopical thin sections Lathes, fitted to foot or power, con- 

 tain COMPLETE APPARATUS for the work. Send lor 

 illus-trated catalogue. Kock sections for sale. 



GUSTAVUS D. JULIEN, 932 Bloomfield St.. HOBOKEN. N. J. 



MARINE BIOLOGICAL LABORATORY 



Sapply Departmeut — 1. Zoology — Preserved Material 



Of all types of animals for class work or for the museum. 

 2. Botany — Preserved Material of Algae, Fungi, Liver- 

 worts and Mosses. For price lists ind all information ad- 

 dress GEO. M. GRAY, Curator A'oods Holl. Mass. 



Ninth Revised Edilion. Published Jan. 190lt. 



The Microscope and Microscopical Methods 



By SIMON HENRY GAQE, of Cornell University. 



Important changes have been made and the chapter on 

 Projection Microscope rewritten and more tuUy illustrated. 

 New figures of American microscopes and apparatus. 

 Postpaid $1.50 as for the 8th edition 



COMSTOCK PUBLISHINQ CO.. Ithaca, N. Y. 



WM. GAERTNER <fe CO. 



Astronomical and 

 Physical Apparatus 

 5347 and 5349 LAKE AVE., :: :: CHICAGO 



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Spectroscopes Comparators 

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Getting Acquainted with the Trees 



By J. HORACE McFARLAND. 



Illustrated, cloth, $1.50 net (postage 18c.) 



"Both delightful and companionable." 



— Times and Despatch. 



THE MACMILLAN COMPANY, Publishers 



NEW LABORATORY AND STUDENT'S BALANCE 

 Large Capacity Higli Accuracy 



Greatest Convenience Low Cost 



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I APPARATUS FOR ELECTR0=0HEMISTS = 



i We have recently established a department to include instruments for = 



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1 We make a most complete line of POTENTIOMETERS, COIL SLIDE BRIDGES, COIL | 



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I THE WILLYOUNG & GIBSON CO., 40 West Thirteenth Street, New York City [ 



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Leuckart=Chun Zoological Charts 



of 



Invertebrates and Chun Charts of Vertebrates 



Price, mounted on linen. Duty Free, $1.75 each 



German Pamphlet on request 



ARTHUR H. THOMAS COMPANY, importers and Dealers 

 Microscopes and Laboratory Apparatus I2th and Walnut Sts., Philadelphia 



