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W. T. BOVIE 
valuable feature. The difficulty has been met by making the instru- 
ment less sensitive. The improved instrument records each o.i mm. 
of growth, and the errors due to the loss of motion of the various parts 
of the mechanism are within the range of other unavoidable errors. 
Making the instrument less sensitive has an advantage for classroom 
work. It has been found that if the instrument is more sensitive the 
Fig. I. A simplified precision Fig. 2. Precision auxanometer, showing ex- 
auxancmeter, ternal details. 
task of counting the checks on the chronometer record and plotting 
the curves requires too much of the student's time. The record of the 
