230 
ASTRONOMY: ADAMS AND STROMBERG 
It should be realized fully that the method of deriving parallaxes from the 
intensities of the spectral lines depends for its accuracy upon our knowledge 
of the parallaxes of the stars used for the determination of the relationship 
between absolute magnitude and line-intensity. It is a process of approxima- 
tion in the early stages of which the corrections may be considerable, but which 
Mc 
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Ms 
4077 
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4072 
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4250 
4269 
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Ms 
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+3 +4 +5+6+7+8 4494 
FIG. 1. CURVES SHOWING THE RELATIONSHIP OF THE SPECTROSCOPIC ABSOLUTE 
MAGNITUDES (Ms) TO THE MAGNITUDES AS DERIVED FROM PARALLACTIC 
MOTION AND MEASURED PARALLAXES (Mc) 
The line intensities upon 
as abscissae. 
which the spectroscopic magnitudes are based are also given 
