206 THE AMERICAN MONTHLY [June 



by Leitz, of Wetzlar. Several of these glasses, construct- 

 ed for the long as well as for the short tube, have found 

 their way into this country, and from the specimens I 

 have seen I am bound to speak highly of their perform- 

 ance. When used with a malachite green screen, the best 

 of these glasses gives an image of remarkable bright- 

 ness, capable of standing fairly high eyepiecing, without 

 appreciable loss of definition. This glass is sold at a 

 very moderate price : in fact, it is, as far as I know, the 

 cheapest glass of the kind hitherto produced. Another 

 objective, which, in its present state of perfection, is new 

 at any rate to me, deserves special mention here. It is a 

 l-12th of hard glass, specially constructed for use in hot 

 climates, by Reichert, of Vienna. It has an aperture 

 rather greater than that of the l-10th first spoken of — 

 perhaps of about 1.35. This objective also is one of ex- 

 ceptional merit ; it is a very strong resolver, and produces 

 an image of great purity and brilliancy, which bears 

 eyepiece amplification remarkably well. It has, however, 

 in my judgment, the important defect that it is adjusted 

 only for a very short tube. If this objective could be 

 corrected for the ten-inch tube, and made to work as well 

 on this as it does on the short tube, I am sure that it 

 .would be found to compare favorably with the majority 

 of fluorite apochromatics, although the latter cannot be 

 purchased for less than double the price which is at 

 present charged for this objective. — From Presidential 

 Address Before the London Quekett Club. 



Second-hand Microscopes. — Beck high class Binocular 

 with 1 1-2, 2-3, 4-10, 1-5, and 1-10 oil immersion lenses with 

 complete outfit is offered for about $80, it being but a frac- 

 tion of the original cost. Also many other microscopes. 

 Clarkson and Co., 28 Bartlett's Buildings, Holborn Circus, 

 E. C. London, England. 



