66o 



LAEORATORY EXERCISES 



system can be rotated from the vertical to the horizontal position by j)ulling out the 

 spring catch E, Fig. 234. 



Fig. 234. — Details of Edinger's drawing apparatus. Z, Drawing board; T, micro- 

 scopic attachment; K\ and A'2 condensers; L, electric lamp attachment. 



For photomicrographic work a camera is clamped to the pillar S, Fig. 234, the 

 plate holder, which will take plates of any size up to 24 by 30 cm., resting on the 



