11 
New Lenses. 
At the request of eminent niicroscopists we have added to the series of our 
apochromatric lenses the following types: 
1) two objectives of very low p o w e r for the purposes of p h o t o - ni i c r o - 
graphy (serial sections etc) and for projection on a screen — viz. 70-iiim 
and 35-mm projection systems; 
2) two objectives of large aperture and a shorter focus (for an 
increased initial amplification) as compared with the older types — viz. 
3-mm apochromatic dry system of 0.95 apert. and 1.5-mm apochromatic 
homogeneous immersion lens of 1.30 apert. ; 
3) an objective having the greatest aperture attainable with the 
present optical means — viz. 2.5-mm monobromide of naphthaline immersion 
objective of 1.60 apert. 
ad 1. The systems of 70 and 35 mm focus serve, as stated above, for 
p h 0 1 0 - m i c r 0 g r a p h y and projection exclusively. Of these the former can 
only be used in conjunction with the photo-microgr aphic stand, the latter, 
however, may be used with any of the other stands. 
The 35-mm lens screws to the lower end of the tube in the usual manner. 
The 70-mni lens requires a special conical adai)ter, which is supplied with 
each lens, to insert it into the upper end of the tube. 
Both are used without eye - pieces. 
As a condenser it is best to use a convex lens of a suitable focus (price of 
lens mounted in sleeve M. 5. — ) to concentrate the rays of the source of light 
upon the objective, so that the pencil of rays emerging from this lens may 
traverse the object before coming to a focus. 
