SCIENCE.— AD YERTISEMENTS. 



X-Ray Apparatus. 



Willyoung Induction Coils witii patent Adjustable 

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 Carbutt X-Ea,y Photographic Plates, etc. 



Write for Illustrated Catalogue 183. 



We make a specialty of equipping scientific laboratories 

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 Psychological Apparatus, Storage Batteries, etc. 



James Q. Biddle, 



Dealer, Manufacturers* Agent and Importer, 



909 Drexel Building, Philadelphia. 



The Thomas A. Scott Fellowship in Hygiene, 

 University of Pennsylvania. 



The Scott Fellowship in Hygiene at the University of Penn- 

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 of applying for appointment to the position can obtain de- 

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 Prof. A. C. Abbott, Director of the Laboratory of Hygiene, 

 University of Pennsylvania, Philadelphia. 



NEW CATALOGUE. 



We have recently issued a new edition, revised and 

 enlarged to 64 pages, of our Catalogue of 



Books on Chemistry, Chemical 

 Technology in Physics. 



It is arranged by subjects, and includes all the 

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 well as the recent literature up to date. 



A copy of this Catalogue will be sent free by mail 

 to any address. 



D. Van Nostrand Company, 



Publishers and Importers of Scientific Boolts, 



23 Murray St. and 27 Warren St., New York. 



Horsford's Acid Phosphate 



Is the most effective and agreeable 

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D. W. W. Gardner, Springfield, Mass., 

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Descriptive pamphlet free on application to 

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Bewart of Substitutes and Imitations. 



For sale by all Druggists. 



The Universuxn Clock 



represents the Universe. It shows the earth revolving round 

 its axis, giving the time at the point passing the sun, the 

 stars in their proper position, and their rising and setting. 



The Nortliern IIexnisph.ere Clocls 



snows at a glance the time at every place between the North 

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UNIVERSUM CLOCK CO., 1 BEACON ST.. BOSTON, MASS. 



HOUGH'S "AMERICAN WOODS" 



A publication illustrated by actucil specimens. Pkepaka 

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 sample specimens. Address 



R. B. HOUGH, LOWVILLE, N. Y. 



in the country to-day offers so high a class 01 

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COLLECTIONS OF MINERALS. 



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MINERALS FOR LABORATORY "WORK. 



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CABINET SPECI MElsrS in greatest variety. 



121-page Illustrated Catalogue, 25c. in paper, 60c. in cloth. 

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GEO. L. ENGLISH & CO., Mineralogists, 64 East 12th St., New York. 



