166 



" Le Diatomiste " ... ... ... ... In exchange. 



" Quarterly Journal of Microscopical Science " Purchased. 



"Journal of the Roval Microscopical Society " From the Society. 



"The American Monthly Microscopical) „ . „,. 



, „ t From the Editor. 



Journal ... ... ... ) 



" The Microscope " ... ... ... ... „ „ 



The President exhibited and described an improved form of his 

 new reflector loup, which he had now achromatised ; it had a focus 

 of nearly lin. and a magnifying power of 12. The optical con- 

 struction and principles of the lens were explained by reference to 

 a diagram drawn upon the board. He also exhibited two new 

 apochromatic low-power objectives, one of ljin. focus by Powell 

 and Lealand, and the other a 36 mm. by Zeiss. He had not yet 

 been able to test Messrs. Powell's, although he had not the least 

 doubt that it was up to their usual standard, but his examination 

 of Messrs. Zeiss's showed it to be a very excellent lens, and he was 

 very glad to find that Continental makers were at last beginning to 

 recognize the use of a good glass of low power. 



Mr. Ingpen said that Zeiss many years ago made low-power 

 objectives of 32 mm. focus, but gave them up soon afterwards, as 

 they said there was no demand for them. He inferred from their 

 bringing out another that they had discovered at last the value of 

 it. As regarded the achromatic loup he felt sure this would prove 

 to be of the greatest value. He was much reminded by these 

 lenses of Zeiss's a*, which it was intended should supersede all 

 other low powers, say from 2in. to 3in. 



Mr. Davis very much admired the reflector loup in its new form, 

 but thought its usefulness would be much increased if it could be 

 fitted with a reflector below the object, to obviate the neces^ty for 

 holding it up to the light. 



The President said that the idea of using it as a lens for field 

 purposes was an after- thought, the original intention being to use 

 it as a dissecting lens, with a small mirror below. The a* was a 

 most valuable lens, but the drawback to it with regard to its use 

 with the microscope was that its apertu e was absolutely nil, and, 

 therefore, it was practically useless. This new lens of Zeiss's with 

 a standard tube was a charming one to use, having a numerical 

 aperture of -186, with a minifying power of x 6 on a lOin. 

 tube — its optical index was 31, and it quite equalled their old 

 English objectives. The only other maker on the Continent who 



