ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



799 



morticed together; a drawing-board (fig. 134, &) made of poplar ; a 

 rackwork arrangement (fig. 134, c) by which the board can be fixed in or 

 altered to any desired position with great rapidity ; and a brass catch by 

 which it can be fixed instantly with a turn of a screw ffig 134, d, e). 

 The advantages of this apparatus pointed out are : (1) it can be raised 



Fig, 134. 



or lowered to any level, and still kept in the horizontal position (figs. 134, 

 136, 138, 139) ; (2) it can be placed obliquely (figs. 135 and 137) ; (3) it 



Fig. 135. 



Fig. 136. 



can be displaced laterally (fig. 138), and obliquely (fig. 137) ; (4) when 

 folded up, the apparatus only takes up a very small space; the measure- 

 ments given by the author are 70 cm. by 55 cm. 



Fig. 137. 



^r/ ^ 



Fig. 138. 



I 



Fig. 139. 



If the rackwork arrangement be made to a curve (fig. 137, a) the teeth 

 will hold more firmly, but this is not necessary, as the apparatus is 

 perfectly steady. 



