GROWTH IN TREES. 



13 



rain does not enter the case. A circular table or base is fitted to the 

 cap, and a drum made of a pection of large brass pipe sits directly on 

 this fitting inside its raised rim, so that it may be removed without dis- 

 turbance of the clockwork. 



The new feature of importance of this cylinder is the manner in 

 which the record paper is attached. The paper is 80 mm. in width and 



FIG. 2. Improved dendrograph lever set. A, inner end of quartz rod in contact with prepared 

 surface on the bark of the tree. The outer end of the quartz rod is fitted with a metal guide which 

 engages the short arm of the recording lever at B. The long arm of the recording lever, D, 

 carries a pen which makes a tracing on ruled paper on a revolving drum. The horizontal member 

 of the frame C, which carries the recording lever, may be toward or away from the tree to adjust 

 the pen at any point on the paper record sheet. 



ruled to millimeters. When placed on the drum the ends are thrust 

 through a slot 1 mm. in width and the free ends are creased on the 

 inside without further fastening. When the drum with the paper so 

 attached is set on its circular base the paper is properly in position 

 when its lower edge is in contact with the rim of the base. A covering 

 as described below is placed over the recorder, but in any case actual 

 rain falling on it would mar only the record and could not damage the 

 instrument. 



The floating frame, however, is exposed to all features of the weather 

 and to the effects of sunlight which might cause its temperature to 

 vary from about C. to 25 C. during the growing season of the trees 



