Growth. 



21 



Make readings hourly throughout the day and on the following 

 day. In this instrument the indicator arm consists of half the 

 beam and a ray of light extending from the mirror to the scale, 

 and it is possible to magnify the amount of growth by 200, or 



Fig. io. Mirror auxanometer. E, metal loop at the end of thread con- 

 nected with apex of stem. The horizontal lever is divided into centimeter inter- 

 vals by deep notches, from one of which the thermometer D is suspended, serving 

 as a counterweight and to indicate temperatures ; C, mirror ; B, set screw for 

 clamping telescoping support. A, levelling screw. 



even 300, and thus detect small increments of growth which 

 may not be measured by any other instrument (Fig. io). 



The mirror auxanometer may be constructed still more 

 simply by attaching a mirror to the lever described in the first 



