halley's comet. 



219 



with the passing of the moonlight we shall not know, for 

 cloudy nights succeeded the waning moon and proved as 

 effectual an hindrance to observation as our satellite's light. 

 At some of the world's big observatories Halley's comet is 

 still (December, 1910) under observation, but to all intents 

 and purposes it has passed from our view, and many years 

 must wax and wane ere it again shines, an interesting object, 

 amongst the stars in our night sky. 



Halley's comet, says Knowledge for March, 1911, is 

 still under observation and is being assiduously followed by 

 Professor Barnard with the forty-inch Yerkes' refractor. It 

 is now of the fourteenth magnitude, round, 32 seconds in 

 diameter, slightly condensed, but without a visible nucleus. 

 It is considerably further from the Sun than when photo- 

 graphed in August [? September], 1909, and yet is two 

 magnitudes brighter, showing that the physical brightening at 

 perihelion persists for some time. Professor Barnard has 

 hopes of keeping it in view till the end of the year ; it will 

 then be far outside the orbit of Jupiter, which it will cross in 

 April next. It will remain invisible for seventy-four years, 

 and will probably be detected in August, 1985, passing 

 perihelion about February, 1986. 



