il SCIENCE.— ADVERTISEMENTS. 
Sclentitic Apparatus 
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Correspondence requested. 
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Dealer, Manufacturer’s Agent and Importer, 
909 Drexel Building, PHILADELPHIA. 
Dec. 1, 1896. Just Published. Sixth Edition of 
THE MICROSCOPE 432, cRoscor 
By SIMON HENRY GAGE, Professor of Microscopy, His- 
tology and Embryology in Cornell University and the 
New York State Veterinary College, Ithaca, N. Y., U.S A. 
Sixth edition, rewritten, greatly enlarged, and illustrated 
by 165 figuresin the text. Price, $1.50, postpaid. 
COMSTOCK PUBLISHING CO., Ithaca, N. Y. 
NEW CATALOGUE. 
We have recently issued a new edition, revised and en- 
larged to 64 pages, of our catalogue of 
Books on Chemistry, Chemical 
Technology and Physics. 
It is arranged by subjects, and includes all the standard 
books in Chemical and Physical Science, as well as the re- 
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A copy of this Catalogue will be sent free by mail to any 
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D. Van Nostrand Company, 
Publishers and Importers of Scientific Books, 
23 Murray St. and 27 Warren St., New York. 
Exhaustor 
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Descriptive pamphlet free on application to 
Rumford Chemical Works, Providence, R. I. 
Beware of Substitutes and Imitations. 
For sale by all Druggists. 
HOUGH’S “AMERICAN WOODS” 
A publication illustrated by actual specimens. 
WOODS FOR THE STEREOPTICON 
Enabling you to show upon the screen characteristic 
structures projected from nature itself. 
WOODS FOR THE MICROSCOPE 
Sections 1-1200 in. thick showing three distinct views ot 
grain under each cover glass. 
WOOD SPECIMENS FOR CLASS USE 
Nothing equals these for use in the class-room. 
VIEWS OF TYPICAL TREES 
From Nature, photographs and stereopticon views. 
WOODEN CROSS-SECTION CARDS 
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If you are interested in wood or trees in any way send for 
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Address R. B. HOUGH, Lowville, N. Y. 
Physical, Chemical, Microscopical and Electrical Apparatus. 
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ZIEGLER ELECTRIC CO., 
Incorporated 
1894. 
“Duty Free” Importations from 
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BOSTON, MASS. 
