212 



cially in cutting sections of hard substances, a lesson on mounting in balsam 

 was given by the lecturer and his assistants, and several slides were prepared by 

 each member of the class ; some Sifted Sponge Sand, and Splinters, and 

 Lucifer Matches were then examined", and their respective structure explained. 



Thursday, February 18th, 1869. 



The subject of Fluid Mounting was commenced, the lecturer's remarks being 

 principally confined to the manipulative portion of the subject. After the 

 process of closing the cell with objects in fluid had been practised by the mem- 

 bers of the class, a number of objects mounted in various fluids were exhibited 

 in the various microscopes. 



Thursday, March 4th, 1869. 



The subject of the last lecture was continued, with especial reference to the 

 fluid media used in the preservation of objects ; their various merits were dis- 

 cussed, and formulae given for making the principal media. The preparations 

 made by the class since the last lecture were examined by the lecturer, and 

 their defects pointed out, and hints given for their prevention. 



Thursday, March 18th, 1869. 



This lecture was entirely occupied by the description of various pieces of 

 apparatus for illumination, and was fully illustrated with suitable objects shown 

 in various ways. 



Thursday, April 1st, 1869. 



Polarisation of Light, with especial reference to its application to micros- 

 copical purposes, formed the subject of this lecture. The phenomena of inter- 

 ference and the changes undergone by a ray of light in its passage through the 

 polarising apparatus, were explained ; the respective merits of various polarising 

 and analysing media were discussed, and apparatus illustrating the subject was 

 exhibited. 



Thursday, April 15th, 1869. 



The processes and instruments used in Microscopic Drawing were described, 

 and opportunities afforded to the members of the class of testing for themselves 

 their respective merits. Various micrometers were explained and exhibited. 

 The uses and capabilities of various drawing materials were discussed, and a 

 brief explanation given of the modes of reproducing drawings by wood and steel 

 and copper-plate engraving, lithography and graphotype. 



A verbatim report of these lectures, illustrated with wood-cuts and revised by 

 ths author, is expected to appear in the Cliemical News about the end of 

 June 



The lecturer was assisted by Mr. F. W. Gay, Mr. W. W. Eeeves, and Mr. F. 

 W. Andrew, who brought their microscopes for demonstration, Mr. Crouch ex- 

 hibited his new Pseudoscopic Binocular ; Mr. Collins supplied microscopes for 

 exhibition, and the Bockett Lamp for the use of the class, besides other 

 apparatus. 



