THE USE OF THE 

 MICROSCOPE 



INTRODUCTION^ 

 MICROSCOPICAL TRAINING 



Accumulation of Errors. — It is certain that there are 

 several dozen forms of error, each of which may entail a 

 loss of perhaps 5 per cent or more in the fineness of detail 

 (amount of resolution) or in the sharpness (definition) of 

 the microscopical image. If the microscopist follows the 

 rules only when the defects from not following them are 

 obvious to him, the image which he sees will doubtless have 

 several unnoticed defects, each causing perhaps up to 5 

 per cent of loss, and these defects may be due to any of 

 50 or more causes. Such defects, in some cases, may 

 total up to even 50 per cent of loss in useful magnification. 

 Therefore one should not drive ahead blindly, but either 

 follow the rules closely or take time to test the effects of 

 any slight departure from them with appropriate test 

 objects. Since much time may be used up in this testing 

 procedure, the writer considers it pays best to obey strictly 

 the laws of optics. This presupposes a knowledge of the 

 rules of scientific microscopy. 



Sequence of Study. — If one proceeds to the use of 

 magnifications of 100 or more without preliminary work 

 with lenses magnifying 2 to 50 times, the connection with the 

 unmagnified world is slender, the microscopical images of 



' This introduction has been planned so that one who has not time to 

 study the whole book may find much that he needs here. Other readers 

 may perhaps postpone the latter part of the introduction till they have 

 read most of the book. 



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