62 
The Light from the Stars [oh. ii 
— 3'4 (Antares) and 7‘4 (Lacaille 8760). Similarly there are no iT-type stars 
between — 0‘8 (Arcturus) and + 5'7 (t Ceti and a Centauri B). 
In 1914 H. N. Russell* confirmed Hertzsprung’s conclusion, using more 
extensive material, and again, in 1917, Adams and Joyf, discussing the 
spectroscopically determined absolute magnitude of 500 stars, reaffirmed the 
B A F G K M 
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Fig. 6. Absolute Magnitudes and Spectral Type of 2100 stars (Mount Wilson Observatory). 
conclusions of Hertzsprung and Russell, finding a distinct division to occur 
in stars of spectral type redder than K 4. Fig. 6 ^ shews the absolute visual 
magnitudes of 2100 stars plotted against their spectral types, and the division 
again shews with remarkable clearness. 
* Nature, April 30, 1914. 
f Astrophys. Joum. xlvi. (1917), p. 313. 
i This diagram was prepared by Mr Hubble and appears in the Carnegie Institution Year-book, 
No. 20 (1921), p. 270.