iv 



SCIENCE.- ADVERTISEMENTS. 



NOTABLE IMPROVEMENTS 

 PROJECTION APPARATUS 



The New Reneotine I.onteni attaoliable to any ITojec- 

 tion Lantern or Stereopticon, for sliowing upon the serepn 

 prints, photos, ent-'ravnijjs, sketches, diagrams, tiowers, 

 Kntomolui^K'al ami Analonucal .specimens, etc., all in 

 natiual colors. Cuts in books may be shown without in- 

 jury totlie book. 



The New Pi-ojeetliie Microscope attachabletoany I'ro- 

 jection l.anlerii or Stereopticon. Projection eye piece. ^le- 

 (liascope for show nit; bujzeniicrospecimensanu cooiin^cell. 



Tllo New Projection !^pcctro*copes and I'oluriseopes 

 attachabletoany rroieotioii Lantern. 



Liiiiterii Sliiles to illustrate Kducational and Scientific 

 .Subjects. We rent slides at low rates. Send for lists, 

 naming particular subject of interest. 



WILLIAMS, IIROVVN &- EARLE, 

 Manufacturers of Stereopticons, Microsroprs, etc. 

 Uepurtineiit H. 918 Chestnut St., Philadelphia 



MARINE BIOLOGICAL LABORATORY 



Supply Department — 1. Zoology — Preserved Material 



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

 2. Botany — Preserved 3Iaterial of Algae, Fungi, Liver- 

 worts and Mosses. For price lists ind all information ad- 

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



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, as 

 it was found impracticable to properly train men engaged 

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

 will begin September 1^9, 1904, and continue for eight 

 months. 



A large corps of teachers in proportion to the number 

 of students makes instruction more directly personal and 

 addiited to the special needs of the individual. The clinical 

 facilities of the University Hospital and other city and 

 eovernment hospitalsare ample, and the laboratories are all 

 well equipped. 



Special attention it invited to the educational advan- 

 tages of thf N;.lional Capital, with its unrivalled libraries, 

 th€ A l iuy Medical Museum, the Museum of Hygiene, and the 

 ,'arious scientific laboratories which are open to students. 



A ciicular of 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. 



Robert Merrick's The Common Lot. sixth Edition 



is one of the strongest novels that has appeared in years. Cloth, $1.50 



THE MACMILLAN COMPANY, 66 Fifth Avenue, New York 



NEW AND IMPORTANT APPARATUS 



By the firm of CARL ZEISS 



APP.\K.\TUS FOR PUOTOMICROGKAPIIY BY .VlElNSOF THE I LTR.l-VIOLKT LIGHT 

 of wave-length 0.275//. A special advantage of lliis metliod is tliat specimens require 

 no staining. Probably the most important advance in applied microscopy since the 

 advent of the homo, immersion objective. 



APPARATUS OF SIEDENTOPF AND ZMGMOXDY FOR THE EXAMI\ATIO> OF nltra 

 microsc(»pic particles in solution. 



EPISCOPE AXD EPIDIASCOPE FOR THE PRO.IECTIO\ OF BOTH OPAQUE and trans- 

 parent objects in natural colors. 



NEW STEREO-COMPARATOR FOR MEASUREMENTS BY THE USE OF STEREO- 

 PIIOTOGtRAPHY in Astronomy, Metronomy, Meteorology, Geology, Topography, etc., etc. 



Prompt information as to Above with Importation Rates upon Application to 



ARTHUR H. THOMAS COMPANY 



Importers and Dealers 



Microscopes and Laboratory Apparatus 



12th and WALNUT STS., PHILADELPHIA 



^Xv cai i y a < <)m|>l('tc slock ol' Bauscli & Loinb Microscojtes, >Iicrott)ines, etc., 

 in l>liilu(1(-l]>hia. Si>c<ial I'acilities lor duty free iinpoitation from Standard 

 i^iiropcaii makers oC I'hysi<-al and Pliysioloy ical Apparalus. 



