SCIENCE 



New Series. 

 Vol. XI. No. i 



Fkiday, February 2, 1900. 



Single Copies, 15 cts. 

 Anndal Sobsceiption, 86.00 



WM. QAERTNER & CO. 



Astronomical and Physical Apparatus 



152-158 EAST 56th ST., CHICAGO 



SIMPLE MICROMETER lor use with 

 our Standard Microscope and Telescope 



SPECIALTIES 



Standard Apparatus of New and Improved Designs 

 Reading Microscopes and Telescopes 

 Astronomical Telescopes Heliostats 



Spectroscopes Dividing Engines, Comparators 



MiCHELSON interferometers GENERAL LABORATORY APPARATUS 



bolometers Ui^IVERSAL LABORATORY SUPPORTS 



MIITIATITRE IITCAITDESCENT LAMPS. 

 MINIATURE LAMP RECEPTACLES. 

 X-RAY TUBES AND APPARATUS. 

 FLUOROSCOPES . -^ 



Catalogues on Application, 



Edison Decorative and Miniatare Lamp Department, 



{Qenekal Electric Company), 



HARRISON. N. J. 



MINERALS. 



Have recently received a lot of Turquois in the gangue rock, 

 15e. to $1.50. The rare Vanadium Mica, Roscoelite, 25c. to 

 §1.50 each ; Hardystonite, 25c. to oOc. ; Caswellite, 10c. to 

 40c. ; Hancockite, 50c. ; Maraposite, 50c. to $1.00 ; Pow- 



ellite, 25c. to 75c. ; Variscite, Utah, 25c. to $5.00 ; Celestite, Lake Erie, 10c. to $2.00. 



WARD'S NATURAL SCIENCE ESTABLISHMENT, 28 to 40 College Ave., Rochester, N.Y. 



I " Biddle's Bulletin " 



is a small pamphlet issued at frequent intervals. It relates to scientific apparatus, 

 chiefly in the line of high grade instruments for Electrical Engineering and Physical 

 laboratories. College professors and others say that they read the Bulletin with 

 much interest. The January number is of special importance ; write for free sample 

 copy. 

 Electrical Measuring Instruments, JAMES Q. BIDDLE, 



Scientific Apparatus, Storage ^^ ^ . „, . r», ..... . 



Batteries, Etc. ^034 Drexel Bldg., Philadelphia. 



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