99 



back to its vertical resting position against the wooden block. 

 It is plain that the recording point of the auxanometric lever 

 itself, which is attached to a growing plant, will make a hori- 

 zontal mark, if allowed to drag across a sheet fixed to the lever 

 arm, or exactly speaking, an arc of a large circle. Since the 

 end of the lever, attached to the plant, is constantly falling as 

 the plant grows, it is obvious that the distance between these 

 marks, which will be made at hourly intervals, will show a record 

 of the growth, amplified of course, in the ratio of the lever arms. 

 The chief difficulty, and this is but a slight one, is in getting the 

 planes of the two levers sufficiently parallel, so that the record- 



a 



f 



\ 



FlG. 2. Sketch to show details of lever-mechanism, a, lever, carrying record; 

 b, wooden block ; c, thread, to which is attached weight, d, and which moves through 

 bent wire pulley, e ; /, pivot ; g, shoulder on which the arm attached to minute- 

 hand spindle, h, impinges ; if the latter is bent once more at right angles, the shoulder, 

 g, need be but a simple pin. The arm, //, is displaced to one side to make the draw- 

 ing clearer. 



ing point will work freely and at the same time not swing away 

 from the surface on which the record is to be made. When this 

 trifling obstacle has been overcome, one has a piece of apparatus 

 which will give a beautifully exact and clear record of hour in- 

 tervals of growth. It will readily be seen that half-hour inter- 

 vals may be obtained by having a double arm or by placing two 



