PROCEEDINGS OF SOCIETIES. 289 



the prism box, by which a very small movement may be imparted to 

 it for the accurate adjustment of the prisms. There are minor details, 

 but these are the principal features of the stand, which is particularly 

 steady and free from vibration. 



Mr. Browning's adaptation of the Stephenson instrument to the 

 Jackson model renders it available for those who wish to use it with 

 a stand of that pattern. The images of the object are reflected to the 

 eye-pieces by two silvered flats, so carefully worked as not to injure 

 the definition. 



Dr. Hudson's transparencies, consisting of beautifully executed 

 drawings of rotifers, were illuminated from behind, and produced an 

 excellent effect, which was enhanced by eloquent verbal descriptions 

 that attracted large audiences. Mr. Tisley exhibited in the same theatre 

 Mr. Spottiswoode's splendid polariscope apparatus, and Messrs. How 

 and Co. showed fine micro-photographs with the oxy-hydrogen 

 microscope. 



Donations to the Library since April 5, 1876 : 



From 



Nature. Weekly The Editor. 



Atheuseum. Weekly Ditto. 



Society of Arts Journal. Weekly Society. 



The Twenty-first and Twenty-second Annual Report of the 



Brighton and Sussex Natural History Society, 1874-75. Ditto. 



Water-colour Drawing of i?o;i-er6«?j/^ia .. .. " W. T. Suffolk, Esq. 



Mon. Eenard and Dr. William Osier were elected Fellows, and 

 Count Castracane an Honorary Fellow of the Society. 



Walter W. Eeeves, 



Assist. -Secretcu-y, 



Watford Natural History Society. 



Ordinary Meeting, March 9, 1876.— Dr. A. T. Brett, Vice- 

 President, in the chair. 



Mr. Arthur Cottam, F.K.A.S., delivered a lecture " On some of 

 the Simpler Methods of Microscopical Mounting," which he illus- 

 trated practically by mounting objects dry and in Canada balsam. 



In treating of the cements employed in dry mounting, he stated 

 that gum-water should be made with perfectly cold water, with a 

 small quantity of alcohol and a little glycerine added ; that a mixture 

 of india-rubber, asphalte, and mineral naphtha formed the best cement ; 

 and that Canada balsam was not to be relied on at all, becoming 

 brittle. 



As an illustration of mounting in Canada balsam, he mounted 

 some diatoms, taking a glass slide, subjecting the diatoms to a dull 

 red heat, placing them in a medium consisting of two parts of balsam 

 to one of benzole, slightly heated, and dropping on the thin glass 

 cover, having previously warmed the slide to prevent its cooling the 

 balsam suddenly, and so producing air-bubbles. 



