LAEORATORY AND TEACHING METHODS 



66l 



drawing board Z (Fig. 234). Having determined the camera extension required by 

 means of a special set screw provided, an allowance of 2.8 cm. is made for the 

 height of the plate above the drawing board. The arm clamping the camera to 



Fig. 235. — Edingti s diawm^ 



icroscopic drawing. 



the pillar is then raised until the collar fits over the draw tube of the microscope 

 body T, or over M, when working with the niicrosummars, thus ensuring a light- 

 tight connection. It is advisable to support the bellows by the strap pieces shown in 



