380 THE WORLD MACHINE 



observer has become familiar with this especial spectral arrange- 

 ment, he may be led to suspect the existence of a nova when 

 it appears in his spectrographs. If then he possesses a series 

 of photographs of the region, he may readily observe whether 

 or no there be any star at this point which had been increasing 

 in brilliancy. All this, it will be seen, is quite outside of the 

 usual work of the observatory. It may be pursued as readily 

 in the library, or floating around on a duck-pond, as on the top 

 of Mount Hamilton, and resembles very much the ingenious 

 method by which Mr. Berenson digs from obscurity unknown 

 painters by means of the tell-tale eyes and ears which they 

 have drawn. 



Could they be close regarded, the blazing up of these nova 

 would doubtless be, in mere extent, the most impressive spec- 

 tacle which the realms of nature afford. The most notable 

 recorded since the days of Kepler was that observed by Dr. 

 Anderson in February of 1901, flashing out from amidst the 

 constellation Perseus. It chanced that this very region had 

 been photographed by the Harvard Observatory several times 

 during the month of February, and up to two days before the 

 star was noted by Dr. Anderson. So we happen to know 

 that it must have risen from a star of below the twelfth magni- 

 tude to a star of the first within about three days. It became 

 the brightest star in the heavens, Sirius alone excepted. The 

 difference of its light within these three days corresponded to 

 an increase of twenty-five thousand fold. 



The apparition faded rapidly but fitfully, until it has be- 

 come visible only as a little star of the twelfth or thirteenth 

 magnitude. The most careful observations have failed to 

 detect for it any parallax or proper motion, so that it is certainly 

 not nearer than a hundred light-years that is, ten times the 

 distance of Sirius and probably very much more. 



After the outbreak the star was found surrounded by a 

 striking nebulosity. This it was possible to photograph, and 

 likewise to make a measure of its apparent diameter. If it be 

 distant no more than a hundred light-years, the extent of the 

 nebula must be at least fourteen hundred times the diameter 

 of the earth's orbit. Professor Young accounts this an under- 

 estimate. 



Repeated photographing of the star brought to light an 

 astounding and almost inexplicable phenomenon. It was ob- 



