ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



255 



finest subjective observation the green light is usually the most useful. 

 Its wave-length almost exactly corresponds with that for which the eye 

 has the greatest adaptability, so that the finest details are seen in the 

 clearest way. So great is the brightness that it suffices for the strongest 

 magnifications. The yellow and the blue light filters will be more useful 

 for studying changes in resolving power. 



The lamp is very simple in management, and can be used for photo- 

 micrography. 



New Microscope Lamp. — This lamp (fig. 37) was exhibited and 

 described at the December Meeting.* By the kindness of the designer, 





Fig. 37. 



C. E. Heath, we are able to add some important particulars and give an 

 illustration. Although not designed for critical work, he suggests that 

 the lamp might be used for that purpose if a ground glass slip were 

 inserted in the lamp, the surface of the ground glass being utilized as 

 the source of light and focused upon the object by the sub-stage 

 condenser. As it is difficult to focus the ground glass, a slip having 

 lines ruled on the ground surface is used for focusing, and when the 

 lines are sharply focused, a slip of ground glass without lines is sub- 

 stituted for it, care being taken that it faces the same way round as the 

 ruled slip, so that the ground surfaces will be in the same plane, and 

 therefore exactly in focus. The ground glass is kept from shifting by 

 the pressure of the curved metal sheet seen in both figures. 



See this Journal, 1911, pp. 128-9. 



S 2 



