18 



* Assorted pairs of Objectives for Binocular Microscopes. 



The combinations PI (Plankton-Searcher), 83, HZ, ao, and one of still lower 

 power, namely of 55 mm (about 2 i / in.) focal length, for use with binocular 

 microscopes are supplied in a special form of setting and mounted in pairs on 

 slides. 



We apply to such pairs of objectives the following distinguishing marks, viz: 



(55), (a7), (), (), (S). 



A pair of suitable diaphragms to slip on, which sho^lld be used whenever 

 it is desired to obtain an image perfectly uniformly sharp up to the margin, is 

 supplied with each set of paired objectives (W). 



For tables of magnification, free working distance and area 

 of visible field of these objectives see p. 21. 



Projection Lenses and Miero-Planars. 



The projection lenses and micro-planars formerly specified in our Catalogues 

 of Microscopes are, as are also the projection eye-pieces, designed for the pur- 

 poses of photo-micrography and projection. For fuller details as to the construction 

 and applicability of these combinations please refer to the new edition of our 

 Catalogue of Photo-micrographic and Projection Apparatus. 



See list of prices on p. 120. 



