8 



CHAP. II. HIGH MAGNIFICATION CRESCOGRAPH 



nearer the fulcrum. The Connector, which joins the first 

 to the second lever, has to be flexible. For this I employed 

 different devices, of which the following is simple and 

 effective. The connection is made by a thin waxed string 

 which has been previously kept stretched for several days 

 by a weight. A moderate tension does not stretch the 

 prepared string any further, nor is the string affected by 

 any hygroscopic change. 



[Z>= 



w 



Fig. I . Compound lever of High Magnification Crescograph. 



, plant attached to arm of lever, l ; l', second lever with bent 

 tip for tracing record ; w, w', balancing counterpoise ; each 

 lever is carried by a fork ; the transverse fulcrum-bar of the 

 lever ends in pin-points which rest in agate cups, one on each 

 side of the fork. 



The attachment of the plant to the first lever may be 

 to the short arm of the lever, in which case the growth- 

 elongation is recorded as a down-curve. It is perhaps 

 more natural to associate upward growth with an up-curve ; 

 this may be secured by attaching the plant to the long 

 arm of the lever (fig. i). The curvature in the record is 

 slight, and is practically neghgible in the middle portion 

 of it. 



