226 HOW TO SEE WITH THE MICROSCOPE. 



ten the reader may perhaps recognize information as to 

 every day work which, perchance, he may turn to some 

 account. There remains therefore but little for us to 

 ndd under the above caption. Without hesitating to 

 repeat in a more condensed form the same ideas which 

 liave heretofore been scattered through our pages, we 

 proceed to give other methods of working with the 

 lower powers. 



First, we use and recommend a stand fitted with a 

 swinging sub-stage, preference being given to the one 

 that will allow the mirror to rise above the level of the 

 stage. Stands there are which although allowing a lim- 

 ited swing, do not afford the extreme range of motion, 

 while scores there be fitted with stationary sub-stages 

 and fittings. Of the last two named, that with the lim- 

 ited range is infinitely to be preferred. One of the prin- 

 cipal advantages arising from swinging the mirror above 

 the stage is that we are enabled thus to condense either 

 sun or artificial light on the top of the object, and it is 

 possible to accomplish this otherwise than by the swing, 

 by simply attaching a mirror to a separate adjustable 

 stand of its own. In whatever arrangement which may 

 be selected, let it be imperative that the mirror be attached 

 directly to the swinging arm, and at the proper focal 

 distance, and that the centre of rotation coincide with 

 the plane of the object on the stage. Any adjustable 

 and intermediate joints between the mirror and the 

 swinging arm, allowing the former to be placed out of 

 ite focal position, is, in the opinion of the author, an 

 intolerable nuisance, and one not to be submitted to un- 



