SCIENCE. 



Electrical Batteries for Medical Purposes. 



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Dr. Butler's Plumbago Rheostat, 



PLIABLE SPONGE ELECTRODES, &c, &c. 



EDISON'S 



Electric Pen & Duplicating Press, 



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8,000 Copies from a Single Writing, at the Rate of 400 an Hour. 



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The New $50 Microscope 



(See Illustration?) 



Write for Catalogue of Magnifying 

 Glasses, Microscopes, Microscopic 

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 croscopic Object Glasses, Micros- 

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Catalogues in 4 parts as follows : 

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From our own experience we can confidently rt commend to all 

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dr. crosby's brain and nerve food, 



The Vitalized Phosphites, 



BECAUSE 



It is largely prescribed by Physicians. 



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It cures Nervous Disorders, especially where it exists with Debility 



By curing Debilily, it prevents Consumption. 



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It gives vigor to the mental and bodily growth of children, and 

 makes a less fretful and happier childhood. 



Every Wholesile Druggist in the U. S. buys it in large quantities. 



SCIENCE 



A. WEEKLY .JOURNAL OF SCIENTIFIC PROGRESS. 



Vol. II, No. 53. - July 2, 1881.; 



CONTENTS. 



The New Comet (Edit.) ; The President's Address before the Royal Microscopical Society, by Dr. Lionel S. Beale, F.R S., 

 (concluded) ; Comet Observations at Princeton ; Letter from A. H. Swinton ; The Blue Color of the Sky ; Professor 

 Dolbear's New Telephone System r Upon a Modification of Wheatstone's Microphone and its Adaptability to Radio- 

 phonic Researches, by Alex. Graham Bell ; Astronomy ; The Lunar Eclipse ; The Ohm ; Alcohol in Air and 

 Water; Elastic Restoration of Caoutchouc ; The Telephonic Receiver ; Alteration of Milk ; Notes; Note from 

 Samuel T. Wallace ; Notice to Correspondents, etc. 



Subscription, Four Dollars a Year. 



Single Numbers, Ten Cents.. 



