xu 



SCIENCE-ADVERTISEMENTS 



A Ne^v Invention 



The Leitz "Binocular Microscope with one objective" 



This instniment causes quite a revolution in the Microscope technique. 



The Binocular Microscope can be used with low and high powers, 

 including Oil-Immersions. 



The body contains a system of prisms whereby the binocular vision with the aid of two oculars is 

 effected. A milled head allows the oculars to be placed at the proper distance to suit the interpupillarity 

 of the observer's eyes. One ocular is supplied with an adjustment for the accommodation of the diJEference 

 of refraction between the eyes of the observer. 



FEATURES 



Restfulness to both eyes. 



Image of increased brilliancy is resolved into the minutest details. 



Apparent stereoscopic effect especially noticeable. 



The regular objectives, available in the laboratories, can be utilized. 



Price complete, without optical equipment, duty free $79.30 



Write for Uterature O-70 



UNITED STATES 

 BRANCH 



30 EAST 18th ST., 

 NEW YORK 



Siemens & Halske 



Repair Shop 



Testing, Calibrating and Repair 



of Electrical Apparatus and 



Instruments 



Btjilding; and Designing: of Special 

 Apparatus for Scientific Investi- 

 gation and Experiments 



New York City 90 West Street 



Buy Science Apparatus 

 Direct From tlie Factory 



Write for the Chapco Purchase Guide No. 11 

 and note the remarkable savings on hish grade 

 Laboratory Apparatus by deahng with first 

 hands — Prompt shipments. Chapco Apparatus 

 is sold direct from factory to schools. *'*^ 



Chicago Apparatus Co. 55 s. Clinton Si. Chicago 



PROVIDENT TEACHERS' AGENCY..^ 

 120 Tremont Street BOSTON, MASSL 



We enroU and we recommend teachen and offioen 

 for public and private schools, for normal and tech- 

 nical schools, and for colleges and universitiei. 

 Vacancies now for immediate service and for 1914- 

 15. Director, JAMES LEE LOVE, formerly of 

 Harvard Faculty. 



ROMEIKE'S 



PRESS CLIPPINGS 



are now an absolute necessity for every scientifio man. 

 By methodical searching through the most important 

 papers and periodicals published in this country and 

 abroad we are able to supply yon at short notice with 

 information on any subject which perhaps you would 

 be nnable to find yourself in libraries or reference 

 books after spending days or even weeks at snoh a 

 task. Write for further information. 



HENRY ROMEIKE, Inc. 

 I06-J 10 Seventh Avenue New York City 



