348 



CENTRAL SCIENTIFIC CO., CHICAGO, U. 8. A. 



No. 8738. 



No. 8746. 



No. 8760. 



8738. 



8746. 



NOSEPIECES, Eevolving, of the circular type, dustproof. They are valuable accessories when 

 the Microscope is supplied with more than one objective, as they save time and prevent dam- 

 age and loss of objectives. When ordered with the microscope, objectives are so fitted that 

 they are par-focal. 



No A B 



Style double triple 



Each $4.75 6.75 



OBJECTIVES, Achromatic, made in accordance with methods first adopted by Professor Abbe 

 by which the complete mathematical formulation of the objective is first perfected, all of its 

 elements clearly determined, such as the actual indices of refraction in the several optical 

 glasses employed, the radii of the curved surfaces, the thicknesses of the lenses and the dis- 

 tances of separation, so that this work of prior calculation does away with all the uncer- 

 tainties of experimental optics. A greater degree of perfection and a much greater uni- 

 formity are thus obtained than it is ever possible to obtain in microscope objectives made in 

 other ways. In these calculations especial consideration is given to securing: flatness of field, 

 critical definition, resolution and long working distance. All objectives are corrected for a 

 tube length of 160 mm and a cover glass thickness of 0.18 mm. Nos. H and J are for oil 

 immersion work. 



C 



No 



Equivalent focus, mm 



Equivalent focus, 

 about, inches 



Numerical aperture . . 



Working distance* 

 with 160 mm tube 

 and lOx eyepiece, 

 mm 



Diameter of the freal 

 field, mm 



Each . 



A 

 48 



0.1 



28 



6.5 

 4.75 



B 



32 



1% 



0.1 



15 



4.7 

 4.75 



1) 

 16 



F 

 4 



1 

 0.25 



9.5 



3.3 

 6.00 



0.5 



1.5 



1. 

 9.75 



O.C 



9.75 







4 



v, 

 0.85 



0.4(i 



0.4 



9.75 



II 

 1.8 



1.25 



0.13 



0.2 

 32.50 



3 



1.5 



1.25 



0.10 



0.14 

 50.00 



* Working distance is the distance between the front lens and cover glass. 



t Real field is the diameter of the circular area seen through the microscope and measured in 



the plane of the object. 



Magnification Table. 

 Tube length, 160 mm. Image distance, 250 mm. 



8760. SLIDES, Microscope, medium thick, 75x25 mm (3x1 inch), made of the best American half- 

 white glass, with ground edges, in boxes of % gross per gross 1.50 



8762. SLIDES, Microscope, same as No. 8760, but 75x50 mm, (3x2 inches) per gross 2.00 



8764. SLIDES, Microscope, extra thin, 75x25 mm (3x1 inch), of white glass per gross 1.90 



