230 The N.Z. Journal of Science and Technology. [July 
The Magnitudes of Stars. 
The British Nautical Almanac for 1918, on page 575, contains the follow¬ 
ing statement as to the magnitudes of the stars : 44 The magnitudes have 
been determined on the assumption that the magnitude of a Ursae Minoris, 
Magnitudes 
if observed in the zenith, would be 245, and that the light given by a star 
of magnitude m is r times that given by one of magnitude m-fl, where 
log. r = 04.” 
If the brightness of a star of magnitude 1 is called 1, then the bright¬ 
ness of a star of magnitude 6 is and a similar relation holds for 
