100 A NEW MICROSCOPE ILLUMINATOR 



It is of special value for examining objects whicli possess light- 

 absorbing surfaces, invisible under vertical light, which are beautiful 

 under the new light. This is easily verified by viewing papers, 

 textiles, leaf rusts, insect wings, potato mould, etc. 



In metals and alloys it shows the depth of penetration of the 

 etching medium, contrast, colour, and as Director Stratton, of the 

 U.S. Bureau of Standards, has pointed out, it enables one to see 

 the slag content of pits which appear black under vertical light. 



The new illuminator may be used without removing the vertical 

 illuminator. By switching the respective lights on in turn, valuable 

 comparative studies may be made. 



The illuminator, when attached to the objective or to a special 

 arm of the stage adapter, may be lowered into hollow objects, such 

 as the steel test dishes used in the enamel industry, or vessels used 

 for the study of pond life, etc. 



The illuminator is attached to the microscope, which may be 

 moved without throwing the light out of adjustment. In photo- 

 graphing it vibrates with the microscope should the latter be jarred. 



The new illuminator eliminates eye strain. The intensity of 

 iiffht which reaches the eye is lower than that produced by other 

 methods. There is no polished disc to interfere with the vision, and 

 only rays reflected by the object examined strike the retina. 



Acknowledgvients. — The writer desires to express his appreciation 

 of the generous co-operation of microscopists who have experimented 

 with the new device. He desires especially to thank your Mr. S. C. 

 Akehurst for the pleasure of his company and valuable suggestions 

 made during his visit to the States, and for his kindness in presenting 

 this paper before the members of your society. 



