CH. /.] 



MICROSCOPE AND ACCESSORIES. 



1 5 



" Tube-length "i 

 Millimeters. 



b-d \ 



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



Various Opticians.* 

 r Pts. included 



in "Tube- 

 _3 length." 

 ^ b See Diagram. 



.c fGrunow, New York 203 mm. 



E. Leitz, Wetzlar 170 mm. 



I Nachet et Fils, Paris . . • ' 146 or 200 mm. 



a-d -j Powell and Lealand, London .... 254 mm. 



I C. Reichert, Vienna 160 to 180 mm. 



I Spencer Lens Co., Buffalo 235 or 160 mm. 



L W. Wales, New York 254 mm. 



Bausch & Lotnb Opt. Co., Rochester. . 216 or 160 mm. 



B£zu, Hausser et Cie, Paris 220 mm. 



Klonne und Miiller, Berlin i6o-i8oor254mni. 



W. & H. Seibert, Wetzlar 190 mm. 



Swift & Son, London 165 to 228^ mm. 



. C. Zeiss, Jena 160 or 250 mm. 



. Gundlach Optical Co., Rochester . . . 254 mm. 



. R. Winkel, Gottingen 220 mm. 



. Ross & Co. , London 254 mm. 



. R. &J. Beck, London 254 mm. 



. J. Green, Brooklyn 254 mm. 



Hartnack, Potsdam 160-180 mm. 



V£rick (Stiassnie) Paris 160-200 mm. 



Watson & Sons, London 160-250 mm. 



Thickness of Cover Glass for Which Non- Adjustable Objectives are Corrected by 



Various Opticians. 



("J. Green, Brooklyn. 

 I J. Grunow, Brooklyn. 

 T 2 B 5 ijmm. \ Powell and Lealand, London. 



I Spencer Lens Co., Buffalo. 

 I W. Wales, New York. 



Watson & Sons, London. 



Klonne und Miiller, Berlin. 

 >' E. Leitz, Wetzlar. 

 \ R. Winkel, Gottingen, Germany. 



Ross & Co., London. 



Bausch & Lomb Optical Co., Rochester. 



C. Zeiss, Jena. 



C. Reichert, Vienna. 

 ( Gundlach Optical Co., Rochester. 

 \ W. & H. Seibert, Wetzlar. 

 (R. &J. Beck, London. 



J. Zentmayer, Philadelphia, 

 f Nachet et Fils, Paris. 

 \ B6zu, Hausser et Cie, Paris. 



Swift and Son, London. 



T %° 5 mm. 



T VVmm. 



16 2 5 ♦« tn 



T y>jrmm. 



15 2 0nim 



if^mm. 



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

 opticians named, or by consulting catalogs. In most of the later catalogs the in- 

 formation is definite, and many makers now not only put their names and the 

 equivalent focal length on their objectives, but they add the numerical aperture 

 {I 29) and the tube-length for which the objective is corrected. This is in accord- 

 ance with the recommendations of the author in the original paper on ''tube- 

 length," CProc. Amer. Soc. Micr., Vol. IX, p. 168. also by Bausch, Vol. XII, p. 



