106 



PROCEEDINGS OF SOCIETIES. 



Microscopical Society, Nov. 9th, 1859. 

 Dr. Lankester, President, in the chair. 



John Stainton, Esq., Longbridge, near Warwick ; M. 

 Foster, jun., Esq., Huntingdon ; J. Burge, Esq., Fulham ; 

 J. L. Bennett, Esq., Pentonvillc-road ; Thos. Hunt, Esq., 

 23, Alfred-place, Bedford-square ; and Jas. Smith, Esq., 

 Soley Terrace, Pentonville, were balloted for and duly elected 

 members of the Society. 



Two papers were read — one by Dr. Greville, 'On Campylo- 

 discus ' {' Trans/ p. 29) ; the other, ' On Diatom acese from the 

 Ohio/ by Professor Hamilton Smith ('Trans/ p. 33). 



Mr. Lobb said — It is with much pleasure I bring before 

 the notice of the meeting the latest production of Messrs 

 Powell and Lealand ; and we are all of us aware how back- 

 ward our friends are to make public their own doings. It is 

 a new achromatic condenser of 170° aperture, having, as in 

 the old one, three combinations, so arranged as to be 

 used separately when required. The diaphragm has eleven 

 apertures, and there are three stops and two semicircles. 

 The stops and semicircles can be placed in any portion of the 

 field, so as to produce the best definition. The movements 

 of the diaphragm and stops arc so contrived as to be adjusted 

 with the greatest ease and freedom, and not, as in all former 

 condensers, placed so as to give the manipulator the greatest 

 trouble to effect the desired end. One thing is required 

 when using this condenser with the full aperture — viz., to 

 have the objects mounted on, as well as count! over with, 

 thin glass; and I think if our object-mounters were to 

 mount all objects in this way on mahogany slides ; it would 

 he far better, and they would be less liable to break 

 than those mounted on glass slides. The delicate markings 

 of the Diatomacese are beautifully defined with this new 

 condenser, using the I, ,',, ami ,'„ object-glasses; the mark- 

 ings on the Aniieian test are made as fully apparent as are 

 those of the Hippocampus; and the delicate lines of P. 



