11 



SCIENCE.— AD YERTISEMENTS. 



K-Bay iwMi 



As sole agent for Messrs. Willyoung & Co., I shall 

 be glad to mail catalogue No. 185 to interested par- 

 ties. It has just been issued, and describes as well 

 as illustrates the most approved modern apparatus 

 for practical production of X-Eays. 



Correspondence is also invited regarding Electrical Meas- 

 uring Instruments, Physical Apparatus, Psychological Appa- 

 ratus and Storage Batteries. 



James G. Biddle, 



Dealer, Manufacturers' Agent and Importer, 



909 Drexel Building, Philadelphia. 



The XJniversu2M. 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 Northern Hemisphere Clock 



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

 Pole and Equator. 



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



HOUGH'S "AMERICAN WOODS" 



A publication illustrated by actual specimens. Peepaea 

 TiONS OP Woods foe Steeeopticon and Miceoscope Speci- 

 mens OP Woods foe Class Use, Etc. If you are interested 

 in woods or trees in any way, send for our circulars and 

 sample specimens. Address 



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



NEARLY READY. 

 THE 



COMMERCIAL ORGANISATION 



Spon 



FACTORIES. 



Full of Diagrams and Practical Points. 



& Chamberlain, 12 Cortlandt St., N. Y. 



Horsford's Acid Phosphate 



Overworked men and women, the 

 nervous, weak and debilitated, will find 

 in the Acid Phosphate a most agree- 

 able, grate%l and harmless stimulant, 

 giving renewed strength and vigor to 

 the entire system. 



Dr. Edwin F. Vose, Portland, Me., says: 

 " I have used it in my own case when suffering 

 from nervous exhaustion, with gratifying results. 

 I have prescribed it for many of the various 

 forms of nervous debility, and it has never failed 

 to do good." 



Descriptive pamphlet free on application to 

 Rumford Chemical Works, Providence, R. I. 



Beware of Substitutes and Imitations. 



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 

 standard books in Chemical and Physical Science, as 

 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 Books, 



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



NO TJEILJ^lETEi. 



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

 Indian Stone Relics as I am now ofiering to 

 advanced collectors, having recently bought 

 several collections, giving every type of Ar- 

 row and Spear Heads from % inch to 7 inches. Drills, Axes, 

 Celts, Pipes, Mortars, Pestles, Hematites, Banner Stones, Amu- 

 lets, also, European Stone Relics. Nothing surpasses and few 

 approach my stock of 15,000 pieces. Goods sent on selection. 

 Catalogue for stamp. Also Catalogue, No. 8, Minbeals, Fos- 

 sils, etc. L, W. STILWELL, Deadwood, South Da . 



COLLECTIONS OF MINERALS. 



Scientifically selected, arranged and labeled. Uneqalled for beauty and practical value.- 



MINERALS FOR LABORATORY "WORK. 



Sold by the pound at very low prices. 



CABINET SPECIMENS in greatest variety. 



124-page Illustrated Catalogue, 25c. in paper, 50c. in cloth. 

 44-page Illustrated Frice-Lists, 4c. ; Bulletins and Circulars Free. 



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



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