PROCEEDINGS OF SOCIETIES. 43 



Mr. Thomas Higgin, some photographs of Atlantic soundings; 

 and 



Mr. T. J. Moore, the spawn of Siredon axolotl, an inhabitant of 

 fresh water from Mexico. 



The usual conversazione concluded the proceedings. 



Brighton and Sussex Natural History Society. 



October 27th. — Microscopical meeting. Mr. T. H. Hennah, Vice- 

 President, in the chair. 



Mr. E. Glaisyer announced the receipt of twelve slides for the 

 Society's cabinet from Mr. Wonfor. 



The minutes of the previous meeting being read, Mr. Hennah 

 called attention to the facility with which sections of bone could be 

 made and mounted by Dr. Ormerod's process, and Mr. Wonfor re- 

 marked that the process applied equally well to such objects as the 

 stones of fruits and shells of nuts. Its great advantages over the 

 other methods were its simplicity and rapidity ; he had made and 

 moimted sections of bone and other hard substances in twenty minutes 

 — a great saving of time compared with the ordinary methods, which 

 often involved hours, without giving so good results. 



Mr, Hennah then introduced the subject of the evening, " Illumi- 

 nation," by remarking that more depended on proper illmniuation than 

 on the instrument or objectives ; good objectives without proper 

 illumination failing to show a proper performance, and inferior ones 

 being made to do a great deal. In the illumination of objects by 

 transmitted light, whatever the apparatus employed, the rays must be 

 parallel. By paying attention to this, almost any structiu'e could be 

 made out by the mii-ror alone, without the expensive sub-stage appli- 

 ances recommended by the opticians. The angle of illumination 

 should never be excessive, in fact should not exceed 90° ; otherwise 

 confusion resulted. Whatever the sub-stage appliance, the light should 

 be exactly focussed on the object. For thick substances direct rays 

 were necessary, but for thin and lined objects oblique rays were 

 essential. The various modes of sub-stage illumination, such as the 

 ordinary and flat mirror, the Nachet and Amici prisms, the achromatic 

 condenser, and the Eeade's prism, were each discussed, preference 

 being given to the Amici, when the sub-stage admitted of its appli- 

 cation. 



Mr. Wonfor then described the different methods for illuminating 

 opaque objects or for obtaining dark-ground illumination, such as the 

 bull's-eye condenser, the Leiberkuhn, parabolic illuminator, Wenham's 

 paraboloid, &c. 



The various methods were afterwards illustrated by Messrs. 

 Hennah, Wonfor, and Dr. Halifax. 



It was announced that the subject for November 24th would be 

 " Bone and Allied Structures." 



November 10th. Ordinary meeting. Mr. Sewell, Vice-President, 

 in the chair. — Mr. Colborne was elected an ordinary member. 



The Hon. Sec. reported the receipt of the ' Annual Eeport and Pro- 

 ceedings of the Belfast Naturalists' Field Club ' from the Hon. Sec, 



