140 



MICROSCOPIC ILLUSTRATIONS. 



fig. 30, with the condenser, m, to condense the light in 

 the manner there represented. 



Fig. 30. 



v. 



If the rays, r, r, make an angle with i, i, similar to 

 that in the former case, the result will be the same. The 

 most convenient plan of managing this mode of illumi- 

 nating by day-light, is by means of a large concave 

 reflector fitted upon the stem of the candle-holder ; or 

 upon a separate stand, so placed that the reflected light 

 shall make the proper angle with the axis of the micro- 

 scope. The instrument, by this means, may be placed 

 in a vertical position, if so preferred. 



The medium power object-glasses, usually marked 

 jB, are best suited for this method of investigation. 



