SCIENCE 
NEw SERIES. SINGLE COPIES, 15 cTs. 
VoL. VI. No. 156. FRIDAY, DECEMBER 24, 1897. ANNUAL SUBSCRIPTION, $5.00 
GENERAL ELECTRIC Co.’s 
NEW X=RAY TUBE 
WITH AUTOMATIC VACUUM REGULATOR. 
Simple. Efficient. Long-lived. Cannot run too high in vacuum. 
CACASASCELHLHLS 
Roentgen Ray Apparatus, catalogue No. 9,050. Minia- 
ture, Candelabra, Decorative Lamps, catalogue No. 9,044. 
Edison Decorative and fliniaturé Lamp Department, 
(GENERAL ELECTRIC COMPANY,) 
HARRISON, N. J. 
186 pages, illustrated with 40 splendid photo- 
The Complete Mineral Catalogue. engravings. Contains a table giving name, compo- 
sition and form of all known minerals, with a supple- 
ment bringing the work up to date; a new classification of the various natural combinations of the metals, showing what 
minerals contain each element; alphabetical index of names; lists giving the specimen values of minerals, ete., ete. 
For the use of teachers, stucents, collectors, mining experts, chemists, and others interested in mineralogy or its practical 
applications. Prices, postpaid ; Paper bound, 2 25 cents; Cloth, 50 cents; Cal/, interleaved, $1.00. Published by 
DR. A. E. FOOTE, 1317 Arch Street, Philadelphia, Pa., U.S.A. Established 1876 
COLLECTIONS OF MINERALS FOR STUDY OR REFERENCE. CABINET SPECIMENS, GEMS. 
Scientific Apparatus. 
It is my business to equip Physical, Psychological 
and Electrical Laboratories. I have ample facilities 
as well as the benefit of more than 10 years’ experi- 
ence. Am closely connected with the best manufac- 
turers in the United States and Europe. 
Particular attention to ‘ Duty Free’’ Importations. 
Correspondence solicited. 
As Special Agent I represent The Electric Storage 
Battery Co., and Weston Electrical Instrument 
Co. Catalogues mailed upon request. 
JAMES G. BIDDLE, 909 Drexel Building, Philadelphia, 
