224 LIGHT SCIENCE FOR LEISURE HOURS. 



for August (see my Stars in their Seasoiis) shows 

 that this constellation lies rather low down towards the 

 north-east a little northerly at 9-45 on August 10, 

 and at 9'30 on August 14. The constellation at those 

 hours is moving ascendingly, and towards the east, 

 remaining above the horizon all night. Meteors of 

 the Perseid system may accordingly be seen at any 

 time of the night : in greater number, but with shorter 

 paths near Perseus ; more scatteredly, but with longer 

 paths at a distance from that constellation. When 

 the moon is new on August 13, the opportunity for 

 observing the August meteors is very favourable. 



Scattered members of the August system may be 

 seen for several days after the track of the main body 

 has been crossed. But, as the direction in which the 

 earth travels changes about one degree per day, science 

 cannot admit that, as Mr. Denning opines (who has 

 done excellent work in the observation of meteors), 

 members of the August system can be recognised by 

 still radiating from the proper ' radiant ' of this system 

 several weeks before and after the time of central 

 passage. To say that a shooting star on September 14, 

 for instance, radiated from the same centre as one seen 

 on August 14, when the earth's course was thirty degrees 

 different, is, for the mathematician, equivalent to 

 saying, not that they belonged to the same, but that 

 they belonged to different meteor systems. 



