128 MICROSCOPIC ILLUSTRATION'S. 



Although this contrivance sufficiently obviates the an- 

 noyance occasioned by tremor, yet I strongly recommend 

 a small stout stand being had expressly for the purpose ; 

 the additional expense not being great, whilst, from 

 its simplicity and convenience, you will be amply 

 recompensed. 



Another purpose to which the steadying rods may be 

 applied, is that of drawing with the camera lucida. In 

 this case, the body of the microscope should first be 

 ranged horizontally, the steadying rods tightened with 

 the clamping screws, and then the requisite adjustments 

 made, the body remaining a fixture. 



Sect. 10. Camera Lucida for drawing with the Micro- 

 scope. — This instrument is constructed in a variety of 

 ways, but the most serviceable is that shewn in the plate, 

 fig. 12. As there is only one reflection, the image of the 

 object is presented to you with its sides reversed, re- 

 sembling a copper-plate engraving from which the im- 

 pression is taken. The method of using this instrument 

 is as follows : — With my microscope, the cap, or cover, 

 which limits the pencil emerging from the eye-piece, 

 must be unscrewed, and the ring, to which the camera is 

 attached, substituted in its stead. This ring is furnished 

 with a pin for the camera prism to slide upon, which 

 may thus be made to approach or recede from the eye- 

 lens to suit the emergent pencils of light. The inclina- 

 tion is regulated by turning it on its axis. 



For making drawings of microscopic objects, the eye- 



