= 68 



With transmitted light the illumination is provided by a mirror with uni- 

 versal motions which is inserted into the base-plate or, with very low magni- 

 fications, simply by means of a sheet of white paper. 



The drawing prism, No. 109, slips over the ocular, but if it is to be used 

 in conjunction with magnifiers or spectacle-lenses, it is fixed to the sides of their 

 holders. 



The drawing board rests upon a frame resembling a desk on the face of 

 which it slides up or down at an inclination of 25. The frame itself slides 

 backward and forward in the groove of the base-plate. 



Scales engraved on both sides of the stage in conjunction with a scale on 

 the base-plate serve to ensure an equal magnification being maintained through- 

 out the process of drawing selected portions of a large object. 



fig. 32. Stand PIT, Drawing Apparatus for low magnifications. 



(V, Full SUe.) 



