1895.] 31ICR0SC0PICAL JOURNAL. 91 



to be moved in a vertical direction, and it should be 

 placed as near the opening in the window as possible so 

 as to receive the sun's rays. The convex surface should 

 be placed toward the sun, and for morning work should 

 be at the right hand of the opening, and in such position 

 as to reflect light towards the microscope, which is 

 placed at the left side of the window and about two 

 feet from the convex reflector, as shown in the figures. 

 Fig. 1 is top view of the plan, and Fig. 2 is a side view 

 of the same; a representing the opening in the window ; 

 d the convex lens and m the microscope. Light from 

 the sun, during the greater part of the forenoon and 

 part of the afternoon will be received by the convex 

 surface near the center of d and will be reflected to the 

 microscope as shown by the dotted line e. 



For work in the afternoon, the convex reflector can be 

 placed at the left of the opening, and the microscope at 

 the right. With this one change, work can be carried 

 on through the greater part of the day. 



Polished glass reflects but a portion of the light that 

 reaches its surface, and the convex form of the reflector 

 disperses the reflected light to such a degree that it 

 gives just the illumination needed for delicate work with 

 very high powers. 



In using an achromatic condensor, I have placed a 

 disk of ground white glass about three-quarters inch in 

 diameter as near the convex surface of the reflector as 

 possible, as shown at c in figure 1. The image of this 

 disk can be focussed upon the object by the condensor. 

 This gives a beautifully clear white light. The ground 

 glass should, of course, be placed between the image of 

 the sun on the convex reflector and the object upon the 

 stage of the microscope. This reflector works well 

 with all forms of illuminating apparatus. A shield 

 should be placed at the opening of the window in 

 such a manner as to prevent the light from the sky 



