December 27, 1889.] 



SCIENCE. 



INDUSTRIAL NOTES. 



The Simplex Duplicator. 



Under the above name is now being manufactured an appara- 

 tus for producing any number up to two iiundred of copies of a 

 letter or othier one-page manuscript, including under tiiis type- 



the Simplex ink on ordinary paper. This is laid face downward on 

 the prepared tablet, and allowed to stay there a half-minute. On 

 removing the sheet, a negative is found on the tablet, from which 

 the desired copies may be obtained by simply applying the sheets 

 of paper one after the other. There is no call for constant inking, 

 as we have already said. 



THE SIMPLEX DUPLICATOR. 



written matter. The accompanying illustration shows the whole 

 thing and the method of working. There is no roller, no inking, 

 no elaborate press. The matter to be multiplicated is written in 



To get rid of the negative, the tablet is put away for a few hours, 

 when all impression from the writing will have vanished. To 

 avoid delay, several plates go with each machine. 



Exchanges 



[Freeof charge to all, ifof satisfactory character. 



-Address N. D. C. Hodges, 47 Lafayette Place, New 

 York.l 



Droysen's Alg&tuetner Historicher Hatid-ntlas (Leip- 

 :zig, 1886,) for scientific books — those published iiT the 

 International Scientific Series preferred.— James H. 

 StoUer, Schenectady, N.Y. 



Astronomical works and reports wanted in exchange or 

 to buy. t^eports of observations on the planet Neptune 

 and its satellite specially desired. — Edmund J. Sheri- 

 dan, B.A., 29s Adelphi St., Brooklyn, N.Y. 



I would like to correspond with any person having 

 Tryon's "Structural and Systematic Conchology " to 

 ■dispose of. I wish also to obtain State or U.S. Reports 

 on Geology. Conchology, and Archceology. I will ex- 

 change classified specmiens or pay cash. Also wanted a 

 copy of MacFarlane's " Geologists' Traveling Hand-Book 

 and Geological Railway Guide." — D. E. Vl^illard, Cura- 

 tor of Museum, Albion Academy, Albion, Wis. 



Morris's "British Butterflies," Morris's "Nests and 

 Eggs of British Birds," Bree's "Birds of Europe" (all 

 colored plates), and other natural history, in exchange 

 for Shakesperiana ; either books, pamphlets, engravings, 

 or cuttings. — J. D. Barnett, Box 735, Stratford.'Canada. 



I have Anodonta opaltna (Weatherby), and many 

 other species of shells from the noted Koshkonong Lake 

 and vicinity, also from Western New York, and fossils 

 from the Marcellus shale of New York, which I would be 

 glad to exchange for specimens of sci-'ntific value of any 

 kind. I would also like to correspond with persons inter- 

 ested in the collection, sale, or exchange of Indian relics.— 



'minerals address W. F. Lerch, No. 308 East Fourth St., 

 Davenport, Iowa. 



A collection of fifty unclassified shells for the best offer 

 in bird skins ; also skins of California birds for those of 

 birds of other localities. Address Th. E. Slevin. 2413 

 'Sacramento St., San Irancisco, Cal. 



I have forty varieties of birds' eggs, side blown, first 

 ■ class, in sets, with full data, which 1 will exchange for 

 books, scientific journals, shells, and curios. Write me, 

 stating what you have to offer. — Dr. W. S. Strodi;, 

 Bernadotte, Fulton County, III. 



I want to correspond and exchange with a collector of 



beetle: 



Tex 



P.O. Box 223, Fredericksburg, VJrgini: 



-Wm. D. Richards 



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Oid and Rare Books. 



Catalogue No. 29 nearly ready. Will contain 

 many scarce works pertaining to Natural His- 

 'tory, Americana, out of print books, as a whole, 

 interesting. 



A. S. CLARK, 



34 Park Row, New York City. 



OLD BOOKS. Catalogue No. 6 Now Ready. Part 

 I. Americana. Part U. Natural Histouv. 

 S. H. CHADBOUKNE, 



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ACK NUMBERS and complete sets of leading Mag 

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Readers of Science 



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OATARKH. 



Catarrhal Deafness— Hay Fever. 



Sufferers are not generally aware that these 

 diseases are contagious, or that they are due to 

 the -presence of living parasites in the lining 

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N.B. — This treatment is not a snuffer an 

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Sufferers from Catarrhal troubles should care- 

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