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ASTRONOMY: W, 5. ADAMS 
The average probable error of the determination of type for these 
four stars is =±=1.0, and this is about the value obtained for several hun- 
dred stars classified in this way. It is evident that the accuracy will be 
FIG. 1. CURVES USED IN STELLAR CLASSIFICATION SHOWING THE VARIATION OF THE 
RELATIVE INTENSITIES OF PAIRS OF LINES WITH SPECTRAL TYPE. THE ORDINATES ARE 
THE DIFFERENCES OF RELATIVE INTENSITY. 
least when the Hnes compared differ greatly in intensity, as in the types 
FO— F9 and K5— Ma, and greatest when the Hnes are of nearly equal 
intensity. 
