iv 



SCIENCE.-ADVERTISEMENTS. 



JDLIEN'S IMPROVED LAPIDARY LATHES 



For SLICING and POLISHING rocks, minerals, fossils, 

 etc., and for GRINDING DOWN the same into micro- 

 scopical thin sections. Lathes, fitted to foot or power, con- 

 tain COMPLETE APPARATUS for the work. Send lor 

 illustrated catalogue. Rock sections for sale. 



GUSTAVUS D. JULIEN, 932 Bloomfield St.. HOBOKEN. N. J. 



MARINE BIOLOGICAL LABORATORY 



Sui)ply Department — 1. Zoology — Preserved Material 



of all types of animals for class work or for the museum. 

 3. Botany — Preserved Material of Algae, Fungi, Liver- 

 worts and Mosses. For price lists and all Information ad- 

 dress GEO. M. GRAY, Curator Woods Holl, Mass. 



Ninth Revised Edition. Published Jan. 1901,. 



The Microscope and Microscopical Methods 



By SIMON HENRY QAQE, of Cornell University. 



Important changes have been made and the chapter on 

 Projection Microscope rewritten and more fully illustrated. 

 New figures of American microscopes and apparatus. 

 Postpaid 81.50 as for the 8th edition 



COMSTOCK PUBLISHINQ CO., Ithaca, N. Y. 



THE SCHOOL OF HEDICINE 

 AND DENTAL DEPARTMENT 



OF 



GEORGETOWN UNIVERSITY, 



in the City of Washington. 



students are required to devote their entire time to the 

 study of medicine. Evening classes have been abolished. »s 

 it was found impracticable to properly train men engaged 

 m other pursuits during the day. The fifty-fifth session 

 will begin September 29, 1904, and contiiiue for eight 

 months. 



A large corps of teachers in proportion to the number 

 of students makes instruction more directly personal and 

 adapted to the special needs of the individual. The clinical 

 facilities of the University Hospital and other city and 

 government hospitals are ample, and the laboratories are all 

 well equipped. 



Special attention is invited to the educational advan- 

 tages of the Nttional Capital, with its unrivalled libraries, 

 the Army Medical Museum, the Museum of Hygiene, and the 

 various scientific laboratories which are open to students. 



A circular ot information giving full details of requisites 

 for admission, etc., will be sent on application to 



GEORGE M. KOBER, Dean, 

 1600 T Street, N. W., Washington, D. C. 



ASK YOUR BOOKSELLER OR NEWSDEALER TO SHOW YOU 



ACMILLAN'S POPULAR SERIES OF TWENTY-FIVE CENT NOVELO 



These include the best fiction of modern times, novels by Mrs. Humphry Wabd, Owen Wistee, 

 Winston Churchill, A. E. W. Mason and others. Price 25 Cents. 



We shall esteem it a favor if you will ask your deahr to show you these 17 novels all of which are now on (ale. 



U'J'Y FREE import scientific instruments free of duty for col- 



leges and universities from Societe Gene'voise, Cam- 

 IMPO R TA TIO N ^^^^^ Scientific Instrument Co. , Max Kohl, Carl Zeiss 

 K^i\i ^1 ly^iy ^^^^^^ fc/e/mann. Otto Wolff 



Hartmann & Braun, Siemens & Halske, and many other sources. 



We shall endea-vor to secure your business on the basis of moderate prices and to 

 keep it on the score of good service. An inquiry 'will recei've a prompt reply. 



THE SCIEmiFIC SHOP albert b. porter 

 SCIENTIFIC INSTRUMENTS 322 Dearborn Street, CHICAGO 



The Hpochromatic Objectives of Carl Zeiss, Jena 



FOCUS N. A. PRICE 



16 mm. 30 dry ... 80. Marks 



8 " 65 " 100. 



4 " 95 " 140. 



2 " 1.30 homo, imm 300. " 



2 " 1.40 " " 400. 



1.5 " 1.30 " " 350. 



Duty Free rate, F.O.B., Phila., 26 J cents per Mark, less 5 per cent, for cash in 10 days. Orders 

 cabled without extra charge. 



ARTHUR H. THOMAS COMPANY, importers and Dealers 



Microscopes and Laboratory Apparatus 



I2th and Walnut Sts., PHILADELPHIA 



