/ O Ot> 



SCIENCE 



New Series. 

 Vol. VII. No. 168. 



Friday, March 18, 1898. 



Single Copies, 15 cts. 

 Annual Subsceiption, $5.00. 



General Electric Co.'s 



New X=Ray Tube 



WITH AUTOMATIC VACUUM REGULATOR. 



Simple.- Efficient. Long-lived. Cannot run too high in vacuum. 



Roentgen Ray Apparatus, catalogue No. 9,050. Minia- 

 ture, Candelabra, Decorative Lamps, catalogue No. 9,044. 



EUlsoQ oecoiative aDl piliilatDie LaniD Depailmeitt, 



(GENERAL ELECTRIC COMPANY,) 



HARRISON, N. J. 



186 pages, 40 splendid engrraviiigs. Con- 

 tains a table giving name, composition and 

 form of all known minerals, witti a supple- 

 ment bringing the wort up to date. Metallic 

 classification showing what minerals contain 

 each element. Alphabetical index of names. Lists giving the specimen values of minerals, etc., etc. For teachers, students, 

 collectors, mining experts, chemists, and others. Postpaid ; Paper, 35 cents ; Cloth, 50 cents; Calf, interleaved, $1.00. 



Established 1876 



Complete Mineral Catalogue. 



DR. A. E. FOOTE, 1317 Arch Street, Philadelphia, Pa., U.S.A. 



COLLECTIONS OF IVIINERALS FOR STUDY OR REFERENCE. 



CABINET SPECIMENS. 



JUST PUBLISHED. 



FACTS ABOUT BOOKWORMS, 



THEIR HISTORY IN LITERATURE AND WORK IN LIBRARIES. 



By J. F. X. O'CONOE, S.J., with Entomological Notes by the late Prof. C V. Riley, of the U. S. Ento- 



mological Commission. Illustrated. 12mo, Cloth, Gilt Top. $3.00, net. 



Only 750 copies handsomely printed at the Gillis press, rubicated title pages, and initial letters. 



The author, as librarian of several large libraries, has had unusual facilities for making a life study of these destructive 

 little creatures. Although written in a popular manner in which the antiquarian predominates, still his suggestions about 

 the care of books, how the 72 varieties of paper-eating insects, which he has examined under the microscope, may be 

 guarded against and destroyed when found, make it of value to all who love or have the care of books. 



Sent postpaid on receipt of price. 



FRANCIS P. HARPER, Publisher, 



17 EAST WTH St., new YORK. 



