PROCEEDINGS OF THE SOCIETY. 835 



The following Instruments, Objects, etc., were exhibited : — 



The Society : —Rock Section, Graphic Granite from Cara Pook, Western 



Australia, prepared by Mr. H. J. Grayson. 

 Mr. T. W. Butcher : — -Slides of Ooscinodiscus asteromphalus ; Lantern 



Slides and Photographs in illustration of his paper. 

 Mr. E. J. Spitta : — Three Lantern Slides illustrating his remarks on 



Mr. Butcher's paper. 

 Mr. J. E. Barnard : — New Photographic Microscope by Messrs. Swift. 



New Fellows. — The following was elected an Ordinary Fellow of 

 the Society : W. E. Garforth ; and the following were nominated as 

 Ordinary Fellows : Hamilton Hartridge, Charles Henry Huish, Malcolm 

 Evan MacGregor, Lewis Noad, Henry Blatch Wells. 



MEETING 



Held on the 15th November, 1911, at 20 Hanover Square, W., 

 H. G. Plimmer, Esq., F.R.S., etc., President, in the Chair. 



The Minutes of the last Meeting, on October 18th, were read and 

 confirmed, and were signed by the President. 



Mr. Rousselet exhibited an old Microscope by Andrew Pritchard, 

 presented to the Society by Captain Warrington. 



At the conclusion of his description of the Microscope, Mr. Rousselet 

 said the Society was very glad to have this old Microscope, as they had 

 no representative of its type in their collection. It was made between 

 1834 and 18:38, at a time important in the history of the Microscope, 

 namely, when lenses first became achromatized. Achromatization of 

 microscopic objectives had been accomplished before 1824, but it was 

 so imperfect that the lenses were no better than those used in the old 

 single-lensed Microscopes. Chevalier, of Paris, was the first to produce 

 an achromatic lens which was serviceable. He did so apparently at the 

 instance of a Mr. Selligue, in 1824, who was the first to place two, three 

 or more of these achromatized doublets, one above the other, to obtain 

 increased magnification ; his plan was to place the convex lens towards 

 the object, but Charles Chevalier soon found that a much better result 

 was obtained by reversing this arrangement and placing the flat surface 

 of the combination towards the object. Between 1830 and 1850 all 

 kinds of combinations of achromatic lenses were tried and made, princi- 

 pally by Tulley, Andrew Ross, James Smith, and Hugh Powell, in this 

 country, eventually resulting in the highly perfected achromatic lenses 

 as we knew them. 



Mr. Rousselet also showed another type of apparatus lent by Mr. A. H. 



