jHe 
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SCIENCE.— AD VERTISEMENTS. 
“ BowDoiN”? X-Ray Focus TUBE. 
My Specialties Are: 
‘““W_S”’ X-Ray Apparatus; Weston Ammeters, Volt- 
meters and Wattmeters; ‘‘Chlorid Accumulator’’ Stor- 
age Batteries; Electrical Measuring Instruments; Phys- 
ical and Optical Apparatus; Pyschological Apparatus, 
ete. 
‘¢ Duty Free’’ Importations from all prominent 
European makers. 
Correspondence requested. 
JAMES G. BIDDLE, 
Dealer, Manufacturer’s Agent and Importer, 
909 Drexel Building, PHILADELPHIA. 
Dec. 1, 1896. Just Published. Sixth Edition of 
THE MICROSCOPE 4%2,™cRoscopl- 
CAL METHODS, 
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 figures in the text. Price, $1.50, postpaid. 
COMSTOCK PUBLISHING CO., Ithaca, N. Y. 
A large collection of Upper 
Cambrian Fossils. Mississippi Cambrian fossils 
from the St. Croix (Potsdam) sandstone for sale. Mostly 
Trilobites. Send for low prices. 
W. A. FINKELNBURG, WINONA, MINN. 
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- 
cent 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 Books, 
23 Murray St. and 27 Warren St., New York. 
Delicious 
Drink 
Horsford’s Acid Phosphate 
with water and sugar only, makes a 
delicious, healthful and _ invigorating 
drink. 
Allays the thirst, aids digestion, and 
relieves the lassitude so common in 
midsummer. 
Dr. M. H. Henry, New Vork, says: ‘‘When 
completely tired out by prolonged wakefulness 
and overwork, it is of the greatest value to me. 
As a beverage it possesses charms beyond any- 
thing I know of in the form of medicine.’’ 
Descriptive pamphlet free. 
Rumford Chemical Works, Providence, R. I. 
Beware of Substitutes and Imitations. 
Eor 12 Cents 
I will mail a finely finished original photo, 
cabinet size, of Sioux Indian Chief, SITTING 
BULL, with his Signature. Have 200 sub- 
jects, all different, of leading Western Indians. 
First-class work. Cabinet Size for 10 centseach. Some sent 
on selection. Givereference. After seeing sample you will 
want others. Indian Costume, Ornaments and Weapons. 
15,000 Flint Stone Ancient Indian Relics. 100,000 Mineral 
and Fossil Specimens. Catalogue forstamp. 18th year. 
L. W. STILWELL, Deadwood, South Dak. 
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 of 
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 
Perfectly adapted to printing (with type or steel plate), 
painting, India ink work, etc. 
If you are interested in wood or trees in any way send for 
our circulars and sample specimens. 
Address R. B. HOUGH, Lowville, N. Y. 
