SCIENCE. 



in 



Electrical Batteries for Medical Purposes. 



V^E£TEF}N J^LECTF[IC ^ANUFyVCTUF{IJ\|Q £o. 



CHICAGO, 



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Manufacturers of and Dealers in 



STATIONARY GALVANIC BATTERIES, PORTABLE HIGH 

 ELECTROMOTIVE FORCE BATTERIES, CHLORIDE 

 OF SILVER BATTERIES, GALVANO-CAUTERY 

 BATTERIES, FARADAIC BATTERIES, POCKET 

 BATTERIES, BATH APPARATUS, AND 

 ELECTRODES= 



Dr. Butler's Plumbago Rheostat, 



PLIABLE SPONGE ELECTRODES, &c. &c 



EDISON'S 



Electric Pen & Duplicating Press, 



pxtrtmely Useful Jnvention 



FOR 



DUPLICATING WRITTEN OR PRINTED MATTER. 



CATALOGUES ON APPLICATION. 



Address all Orders to 



Western Electric Man'fg Co. 



38 Union Square, 

 — NEW YORK — 

 CITY. ^ 



,000 Copies from a Single Writing, at the Rate of 400 an Hour. 



. is successfully used by Schools, Colleges, Banks, Commission Houses, Mercantile Firms, Lawyers, 

 linisters. Copyists, and every' person or firm desiring a number of duplicates of any document. 



10,000 fens now in JJse and tfye pemand jSteadily jncreasing ! 

 No. 1, $25.00; No. 2, $30.00; No. 3, $35,00- 



Full Description and Samples of Work sent on Application. 



EDISON'S ELECTRIC PEN AND PRESS, 



38 Union Square. New York City. 



James W. Queen & Co., 

 OPTICIANS, 



924 Chestnut St., Philadelphia. Pa. 



Magnifying Glasses, Microscopes, 

 Mounting Materials, Insect Pins, 

 etc., etc. 



Catalogues sent on Application. 



Part 1st, Mathematical Instruments. 



" 2d Optical Instruments. 



" 3d Magic Lanterns and Slides. 



" 4th Physical Instrument. 



FOR SALE CHEAP. 



A Zentmayer Binocular Centennial 

 Stand, and large amount of accessories 



List Price $580. Will be sold for $310. 

 J. W. S., care of Office of " Science." 



SCIENCE 



A. WEEKLY JOURNAL OF SCIENTIFIC PROGRESS 



Vol. II. No. 43, 



April 23, 1 88 1 



CONTENTS. 



Abstract Science in America ; The Ohio Mechanics' Institute ; Scientific Societies of Washington ; On the Modern De- 

 velopment of Faraday's Conception of Electricity, by Professor Helmholtz ; The Yellowstone Mational Park ; Mean 

 Temperature at Boston, Mass., from the Report of the Chief Signal OtTicer, Washington; Note on the Sensory Tract 

 of the Brain, by Edward C. Spitzka, M. D.; Intr.i-Mercurial Planets, by Professor Lewis Swift ; Discrepancies in 

 Recent Science, by Professor A. E. Dolbear ; Discrepancies in Recent Science, by Dr. George W. Rachel ; Notes, 

 Astronomical, Chemical, Microscopical, Physical, &c, &c, &c. 



Subscription, Four Dollars a Year. 



Single Numbers, Ten Cents. 



