95 



length. If for any work J inch or higher powers are 

 desired, the solid eye-pieces may be recommended. 

 The periscopic are advantageous for micrometric 

 tests and other work where a large or flat field is 

 desirable. 



For student's and practitioner's use, the outfits as 

 made up in catalogues are usually sufficient, except, 

 as above recommended, where but one eye-piece is 

 given, it is well to select two where means will permit. 



Referring particularly to the catalogue of the 

 Bausch^c Lomb Optical Co., we will state the purpose 

 for which they were intended 



Biological Laboratory, student and professional 

 use. 



Large Biological Advanced laboratory, student and 

 professional use. 



Harvard Laboratory, student and professional use. 



Model Laboratory, student, professional and ama- 

 teur use. 



Physician Professional. 



Investigator Student, professional and amateur use. 



Universal Student, professional and amateur use. 



Concentric Professional and amateur use. 



Professional Advanced laboratory, professional 

 and amateur use. 



For ordinary professional use, including urinary 

 examinations, the J inch 27 degrees and \ inch 110 

 degrees objectives will be found sufficient. For 

 bacteriological examinations a higher power, such as 

 a ^ inch homogeneous immersion, objective will be 

 necessary. 



