CH. II] 



LA BORA TOR Y MICROSCOPES 



71 



Fig. 70. Krauss' Method of 

 Marking Objectives on a Revolving 

 Nose-Piece. 



As seen in the figure, the equiv- 

 alent focus of the objective is en- 

 graved on the diaphragm above the 

 back lens and may be very readily 

 seen in rotating the nose-piece. This 

 is of great advantage \ as one can see 

 what objective is coming into place 

 without trouble. It is also an ad- 

 vantage in showing where each ob- 

 jective belongs when the microscope 

 comes from the manufacturers. The 

 method is coming into general use. 



FIGURES OF LABORATORY AND HIGH SCHOOL 

 MICROSCOPES 



In order that teachers and students may get a good general idea of the appear- 

 ance of microscopes of various makers for high school and advanced laboratory 

 work a few pictures are appended of the microscopes most used in the United States- 

 This has been rendered possible by the courtesy of the manufacturers or import- 

 ers. It will be seen that the microscope for the advanced laboratory work is on 

 the left and the cheaper one for school and less advanced laboratory work is on 

 right. The microscopes are arranged in alphabetical order. 



Laboratory microscopes which will answer nearly all the requirements for 

 work in Biology, including Histology, Embryology, Pathology and Bacteriology, 

 are listed in the makers catalogs at about $ 100.00. The less expensive micro- 

 scopes shown on the right are listed at $25 to $ 45. There is usually a discount of 

 10% or more from these prices. Fortunately in the State of New York the State 

 pays half for high school apparatus, so that there is no reason why every high 

 school should not be properly equipped with microscopes of a good grade. To 

 avoid misunderstanding it should be added that the quality of the oculars and 

 objectives on the high school microscopes figured is the same as for the best 

 laboratory microscopes. The mechanical work also is of excellent quality. 



During the last ten years great vigor has been shown in the microscopical 

 world. This has been stimulated largely by the activity in biological science and 

 the widespread appreciation of the microscope, not only as a desirable, but as a 

 necessary instrument for study and research. The production of the new kinds of 

 glass, (Jena glass), and the apochromatic objectives has been a no less potent 

 factor in promoting progress. The stadent is advised to write to one or more of 

 the opticians for complete catalogs. (See list, p. 2 of cover). 



