In purchasing a microscope a beginner may be 

 easily misled by the enticing appearance of an object, 

 which may be due not so much to the instrument as to 

 the object itself and if the optical parts are inferior, it 

 will require but a short experience to become convinced 

 of it usually as soon as a comparison can be made with 

 reliable work. The investment in one of these objec- 

 tives is not only a source of disappointment, but usually 

 proves to be a pecuniary loss, as it is generally followed 

 by a fresh outlay in responsible work. It is of ordinary 

 occurrence that such objectives have been sent to the 

 writer's firm with the request to examine them and 

 rectify the faults ; but an examination almost invariably 

 proves that the cost of doing so is considerably greater 

 than that of a new objective of the same power and it 

 would not even then be equal to the latter. 



Accessories. We have already stated in the 

 body of this book which kinds of accessories are con- 

 sidered useful. Some of them are absolutely necessary 

 in some special lines of work, in which case, however, 

 the student is generally conversant with the require- 

 ments and may make a suitable selection, but for all 

 general purposes some accessories are necessities where 

 others are only conveniences and we append a list of 

 such which, unless prohibited by necessity, should 

 accompany each outfit. 



Abbe substage condenser, preferably the complete 

 substage attachment giving all adjustments. 



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