6 



MICROSCOPE AND ACCESSORIES. 



Length in Millimeters and Parts Included in "Tube-Length" by 



Various Opticians* 



Pts. included 

 in "Tube- 

 length." 

 See Diagram. 



Grunow, New York 203 



Nachet et Fils, Paris 146 



a-d ■{ Powell and Lealand, Loudon .... 254 



C. Reichert, Vienna 160 



W. Wales, New York 254 



Bausck & Lomb Opt. Co., Rochester .216 



Bezu, Hausser et Cie, Parisf 220 



Klonne und Miiller, Berlin i60' 



W. & H. Seibert, Wetzlar 190 



Swift & Son, London 165 



C. Zeiss, Jena 160 



. Gundlach Optical Co., Rochester. . . 254 



. R. Winkel, Gottingen 220 



. Ross & Co., London 254 



. R. & J. Beck, London 254 



. H. R. Spencer & Co., Geneva, N. Y. . 254 

 . J. Green, Brooklyn | 254 



f E. Leitz, Wetzlar 125 



\ For oil immersions 160 



c'-e 



Tube-length " in 

 Mdlimeters. 



mm. 



or 200 mm. 



mm. 



to 180 mm. 



mm. 



mm. 



mm. 



■180 or 254 mm. 



mm. 



to 228^ mm. 



or 250 mm. 



mm. 

 mm. 

 mm. 

 mm. 

 mm. 

 mm. 



-180 mm. 

 mm. 



Fig. 8b. 



Thickness of Cover Glass for which Non- Adjustable Objectives are Corrected 



by Various Opticians. 



'J. Green, Brooklyn. 

 J. Grunow, New York, 

 mm. -i Powell and Lealand, London. 



H. R. Spencer & Co., Geneva, N. Y. 



W. Wales, New York. 



Klonne und Miiller, Berlin. 



F. Leitz, Wetzlar (when tube 160-170 mm.). 



R. Winkel, Gottingen, Germany. 



Ross & Co., Loudon. 



Bausch & Lomb Optical Co., Rochester. 



C. Zeiss, Jena (j^mm. for apochromatic oil immersions). 



C. Reichert, Vienna. 



; Gundlach Optical Co., Rochester. 

 W. & H. Siebert, Wetzlar. 

 R. & J. Beck, London. 

 J. Zentmayer, Philadelphia. 

 ( Nachet et Fils, Paris. 

 \ Bezu, Hausser et Cie, Paris. 

 Swift & Son, London. 



25 

 TOO 



roVnm. 

 iVoinm. 



xVo mm - 



Hfmni. 



To 6 o mm - 



4~<nf mm - 



15 



100 



4*1^ mm - 



105 



_io_ 

 100 



§ 18. Aperture of Objectives. — The angular aperture or angle of aperture of au 

 objective is the angle "contained, in each case, between the most diverging of the 

 rays issuing from the axial point of an object [i.e., a point in the object situated 

 on the extended optic axis of the microscope], that can enter the objective and 

 take part in the formation of an image." (C.) 



*The information contained in these tables was very kindly furnished by the opticians named, 

 t Successors to Hartnack. 

 % Successor to Tolles. 



