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PROCEEDINGS AT MR. SUFFOLK'S CLASS. 



Thursday, January 7th, 1869. 



The lecturer, after briefly explaining the Laws of Refraction and Reflection, 

 proceeded to demonstrate the properties of lenses and their application to the 

 construction of various optical instruments, such as the Camera Obscura, 

 Telescope, and more especially the Microscope. The employment of single 

 lenses as microscopes was explained, and some useful hints respecting the use of 

 the hand magnifier given The combination of lenses in the compound instru- 

 ment was illustrated, and Chromatic and Spherical Aberrations explained. The 

 Binocular instruments of Messrs. Wenham and Powell and Lealand, were 

 mentioned, and the advantages to be derived from their use strongly urged. 



The subject of Lamps next engaged the attention of the lecturer, and the 

 respective merits of Gas, Oil, Paraffine, and Camphine were fully discussed, 

 and attention was directed to various lamps supplied by Mr. Collins. After a 

 few remarks on the care of the instrument, and cleaning the lenses, &c., the 

 members of the class were required to examine air bubbles and oil globules, 

 and note their various appearances ; they were then exercised in the examina- 

 tion of a few simple substances by reflected light. 



Thursday, January 22nd, 1869. 



This lecture was devoted exclusively to certain mechanical processes in connec- 

 tion with microscopical operations, such as cutting glass with the diamond, 

 drilling holes in glass, the use of corundum grinding tools, the mode of clean- 

 ing slides and thin glass, and bending and drawing glass tubes. Cementing 

 with marine glue, the manufacture of cells and troughs, and the bending, tem- 

 pering, and otherwise utilizing needles and other small pieces of steel were also 

 explained. 



The objects examined were— Sole Skin, Feathers of Peacock and Humming 

 Bird, with especial reference to the importance of the direction of the illumin- 

 ating pencils. Bread crumbs were also examined in various ways, as recom- 

 mended for a preliminary lesson by Dr. Beale. 



Thursday, February 4th, 1869. 



The processes of Dry Mounting in various ways were explained and illustrated 

 practically by the lecturer, modes of drying tissues were mentioned, and a new 

 process at present being experimented upon with a view to its adaptation to 

 microscopical purposes described The nature and properties of Canada 

 Balsam, and its uses as a mounting medium, were treated upon at length. The 

 objects suitable for treatment with balsam, and the preparation required before 

 mounting, were described. After stating the various advantages to be derived 

 from the use of this medium , and also its defects and its use as a cement, espe- 



