Variable Stars. 77 



A new variable in Cams Major has a range only from magnitude 

 5. 9 to 6.7. Its period is 1 day, 3 hours, 15 minutes and 55 seconds. 

 Its light curve may be represented thus : 



22 h. 5.9 mag. 



It will be seen that out of 27 ^ hours this star has only 5 hours 

 of partial obscuration. 



How are these magnitudes determined with such precision to a 

 decimal of one-tenth? Simply by interposing between the star and 

 the eye a wedge of neutral tinted glass. This wedge, or light 

 gauge, or photometer, is six inches long, and thick enough at one 

 end to obscure the brightest stars. Its thin edge is placed at the 

 eyehole of the telescope and then pushed along till t ;e star under 

 examination just disappears, when the scale on the edge is read 

 and the star's magnitude determined. 



Now in the case of Algol there are two neighboring stars just 

 below the fourth magnitude, called respectively Gamma and Delta, 

 the latter being the fainter. It has been found that Algol has the 

 same brightness as Gamma 1 hour and 21 minutes before the true 

 minimum, and 1 hour and 4 minutes after the true minimum; and 

 that it has the same brightness as Delta 54 minutes before and 

 64 minutes after true minimum. We learn from this that the light 

 diminishes more rapidly just before the minimum than it recovers 

 after. 



How shall we account for these, strange fluctuations of brilliancy 

 in those distant orbs? We must first bear in mind that each one 

 of those tiny points of light is a great flaming sun like our own — 

 the seat of inconceivably fierce combustion; or the nucleus of an 

 energetic condersation of a vast mass of nebulous matter; whether 

 gaseous or meteoric. 



Are these fluctuations in brilliancy, then, due to a greater or less 

 activity in the combustion agitating the surface of the distant sun, 

 or are they due to an increased energy in the condensation of the 

 nebulous mass which is forming a new sun ? Or is the periodical 

 obscuration of light observed in many stars caused by the interven- 

 tion of dark bodies revolving around the distant sphere and par- 

 tially eclipsing it? 



