Miscellaneous, 469 



interesting localities about Liverpool for the study of Natural 

 History. Arrived there they divided into parties of about thirty 

 each, to explore the neighbourhood. One division vras lead 

 by a geologist qualified to explain the nature of the surrounding 

 strata ; another by two or three proficient botanists ; and the 

 third by a gentelman whose name is known to the students of 

 microscopical science. After rambling about and investigating 

 the natural curiosities of the neighbourhood (during which time 

 many curious specimens were obtained), the parties met at a 

 charming little spot in the vicinity called Raby Mere, and par- 

 took of a homely but plentiful tea in a garden attached to a farm- 

 house. At this stage of the proceedings a prize was awarded accord- 

 ing to previous arrangement, to a young lady, for the greatest 

 variety of wild flowers collected during the ramble ; and several 

 beautiful specimens of plants and insects, as well as a fine viper, 

 were examined by the excursionists with interest. A Commettee 

 meeting was then held in the open air, when it was determined to 

 ofler a prize on the occasion of each excursion ; the next field 

 meeting was fixed and a great many new members were proposed. 

 The Society already numbers nearly 200 members and promises 

 to be the most extensive of the kind in England. The eqcursion- 

 ists returned home delighted with their days ramble. We may 

 mention for the government of other clubs of this kind, that more 

 that the third of those present were ladies, who were deeply inte- 

 rested in all the proceedings. — Athenoeum. 



New form of Microscope. 



* On Microscopic Vision, and a New Form of Microscope,' by 

 Sir D. Brewster. — In studying the influence of aperture on the 

 images of bodies as formed in the camera, by lenses or mirrors, it 

 occurred to me that in microscopic vision it might exercise a still 

 more injurious influence. Opticians have recently exerted their 

 skill in producing achromatic object-glasses for the microscope 

 with large angles of aperture. Tn 1848 the late distinguished 

 optician, Mr. Andrew Ross, asserted "that 135° was the largest 

 angular pencil that could be passed through a microscopic object- 

 glass," and yet in 1855 he had increased it to 1*70° ! while some 

 observers speak of angular apertures of 1*75°. In considering the 

 influence of aperture, we shall suppose that an achromatic object- 

 glass with an angle of aperture of 1*70° is optically perfect, repre- 



