New S&ries 



Vol. LV, No. 14];; 



Friday, January 20, 1922 f^^i-^ Copies, 15 Cts. 



' ' Annual Subscription, $6.00 



Immersion Objectives 



for Dark-Field Microscopy 



A FULL examination of dark-field condensers of 



makes has brought out the fact that the leasj 

 aperture for the objective to use with them is about 0. 

 the December 9th issue of Science, Simon H. Gage ' 

 work leading up to this conclusion. 



These new Bausch & Lomb objectives are of oil immersion type, 

 1.9 mm equivalent focus, 0.80 N. A. They are most useful, in 

 biology or in medicine, to the v/orker who wishes to realize the 

 peculiar advantages offered in dark-field illumination. Furthermore, 

 they serve well for ordinary bright-field work, and results compare 

 most favorably with the usual high-apertured objectives of this 

 power, as ordinarily used with the Abbe condenser not in immersion 

 contact with the slide. 



Delivery of these objectives can be made immediately. They 

 are listed as follows: 



Cat. No. 



1042 Achroinatic Objective, 



1044 Fluorite Objective, i.8 



Price 



1.9 mm, 0.60 N. A $40.00 



mm, 0.80 N. A 55.00 



Special Microscope Lamps for Dark-Field Microscopy are described 

 in a parapidet ivhich icill be sera on request. 



409 St. Paul Street, Rochester, N. Y. 



New York Washington Chicago San Francisco London 



Leading American Makers of Pliotosrapltic Ler-.-s Virrascopes, Projcc 

 Lenses and Instruments P' otomicrograplu ipparatus. Range Findcn 

 Sca-chltgltl Rellertorf S ereo Pr /r E.nocniars, Magnifiers and 



n Apparatus (Balopticons) , Ophthalmii 



ind Oun iight, for Ann-, and Nai-,, 

 er high-grade Optical Product.. 



Wat e^es Tiny see '^ 

 ~^_Jjetter cnl farther -^^ 



