SOME RECENT ASTRONOMICAL EVENTS. 169 



of this displacement in Plato III, already referred to. Later photo- 

 graphs show a continuation of the rapid expansion of the nebula. The 

 astonishing magnitude of this motion becomes more appreciated when 

 it is said that the greatest displacement or proper motion of a star so 

 far observed in the whole universe is less than 9 seconds per annum, 

 or less than one-seventieth part of the rate of motion of the nebula 

 surrounding Nova Persei. This great disparity has led some to think 

 it is the propagation of light and not of material which is made 

 apparent. 



What further of interest Nova Persei has in store for us we can not 

 foretell, but up to the present time its appearance and subsequent his- 

 tory have deserved to take rank as the foremost astronomical event of 

 the year. 



