12 



Smith, on a Dissecting Microscope. 



rests let down and when not in use — and it is made complete 

 as a box by a piece of wood (similar to that forming the back) 



No. 2. 



w 



which drops into a groove in front of the drawer and is fastened 

 by small hooks at the top to the stage, and upon this piece the 

 condenser can conveniently be fixed by catches when the 

 instrument is packed up I have thought it better to make 

 this front a separate part, as it might sometimes be found very 

 much in the way if permanently fixed on by hinges. I have 

 not shown it in the drawing, thinking it unnecessary to do so. 



Drawing No. 2 also shows the small dark tube devised by 

 Dr. Carpenter, for facilitating dissection without the aid of 

 the glasses, and described at page 192 of his work on the 

 Microscope. This tube (the adding of which as a part of my 

 apparatus I am indebted to him for suggesting) has a piece 

 of ground glass fitted into the bottom, and can either be used 

 for the purpose more immediately intended, or for softening 

 the light, which is often very necessary when working at night 

 with a lamp or candle. 



As a fitting addendum to the description of my microscope, 

 I may here give that of a modification of the ordinary dis- 

 secting trough, suggested to me by Professor Busk, who has 

 kindly permitted me to add it to my paper. The new trough 

 is made by cutting a small piece (say for example one inch 

 long and a quarter of an inch in width) out of the centre of 

 a gutta-percha one, and inserting in the hole thus left a piece 

 of glass, so as to be on a level with the surface ; by this 

 arrangement, the object to be dissected, after being cut open, 

 can be fastened do^Ti over the glass by pinning it to the 

 gutta percha on either side, and in this way it can be illumi- 

 nated either by the condenser or the mirror, as may be 



