APPENDIX. 



353 



lower, a view from above, of the camera arranged for 

 use). The edge (a) of the prism of the side A of the 

 camera covering half of the upper lens of the ocular. 



FIG. 7. 



In front of the microscope, the drawing-board is placed 

 at an angle of 15 20 with the surface of the table. 

 On looking down the microscope both the object and 

 the drawing-board are seen. The illumination of 

 the drawing-board and of the field of the microscope 



L. 23 



