A NEW OPHTHALMOSCOPE. 



89 



"developing" proves that a good "negative" has been obtained, it 

 is "fixed," and used for printing the photographs; if not, other 

 plates are used until a more satisfactory result is obtained. 



AS AN OPHTHALMOSOOPE. 



37te potitionof the instrument when the light is supplied by a lamp:—! the camera, 2 

 camera tube, 3 illuminating tube, 4 diaphragm with central aperture, 5 slide with 

 ground glass, 6 glass chimney of lamp, 7 brass tube four inches in diameter which acts 

 as a shade and from which projects 8 a brass collar opposite the flame of the lamp and 

 to which is adapted 3 the illuminating tube of the instrument, 9 upright of the lamp 

 •tand, 10 eye-piece containing a camera lens of three inch focus to be adapted to the free 

 extremity of the camera tube, when the eye-piece is used the camera is dispensed with. 



In using this instrument as an ophthalmoscope, that is, for exami- 

 ning the interior of the eye, artificial light is used. The light from 

 a kerosine oil lamp answers very well, but the best light for ophthal- 

 moscopic purposes is from the gas-argand-burner, and the most con- 

 venient is the moveable table lamp, supplied with gas through a flex- 

 ible tube. The evening is the best time for making these examina- 

 tions ; if in the day time, the room is darkened. The instrument is 

 placed in the same position in regard to the light as when solar light 

 is used, but the flame of the lamp is brought within 2 or 3 inches of 

 the entrance of the illuminating tube, and the two are placed on the 



