D. J. SCOURFIELD ON ASHES CAMERA LUCIDA. 



415 



A second point to be noted is with regard to the kind of mirror 

 to be used. After several trials it has been found that a small 

 cover-glass, say, about half an inch in diameter, silvered on one 

 side and cemented to a thin metal plate, gives excellent results, 

 and seems altogether the simplest and most suitable form of 

 mirror for this camera. 



As regards the neutral tint glass it is necessary to make it 

 rather large, because, owing to the adjustments which have to 



B, Body of camera, fitting over eye-piece. 



F, Front plate, with central aperture. 



E, Eye. 



3f, Mirror, pivoted at x, and rotated by a milled head indicated 



by the dotted circle. 

 N, Neutral tint glass, pivoted at a?' and rotated by a milled head. 

 O, Object. 

 P, Pencil and paper. 



The above diagram shows the positions of the mirror and neutral tint 

 glass when the camera is used with the microscope inclined at an angle 

 of 45°. 



be made for various inclinations of the microscope, the light is 

 not always reflected from the same spot. In addition to this it 

 is evidently essential that the whole image of the field, as seen 

 on the drawing-paper, should be visible through the neutral 



tint glass. 



