THK NKW STAR. 
179 
showing the bright lines, receding from us, and the other, 
showing the corresponding dark lines, approaching us. 
The spectrum of Nova Persei reveals a similar condition 
of things. Several theories have been advanced to explain 
this singular phenomenon, but the one now generally ac¬ 
cepted was advanced by Seliger, soon after the appearance 
of Nova Aurigse. This theory is, briefly, as follows, and 
is based upon the now unquestioned existence of dark stars. 
A dark star and a nebula, moving in opposite directions, 
encounter each other with a relative velocity estimated at 
from 500 to 700 miles per second. The friction thus caused 
would develop a tremendous amount of heat energy, suffi¬ 
cient to render the surface of the dark star incandescent, 
and in all probability sufficient to vaporize a portion of it. 
The nebulous mass would also be heated by the impact and 
likewise glow. According to the Scientific American, 
“there are strong reasons for suspecting that the recent 
outburst in Perseus represents ah occurrence of this sort, 
and that the star and nebula will disappear from view after 
a few weeks or months.” 
Photography has recently played a very important part 
in the study of the stars, as the camera will often detect a 
star that eludes the eye, even with the best modern instru¬ 
ments. In fact, two Novae were discovered by the photo¬ 
graphic plate, one in 1893 and another in 1895, at the Har¬ 
vard College station in South America. When these were 
examined with the spectroscope, they showed the same 
bright and dark lines as those above mentioned. This 
leads Professor Young to remark: “It now seems rather 
probable that 'new stars’ are not really extremely rare, and 
it is clear that there are important physical resemblances 
between them.” 
When the news of the discovery of Nova Persei was re¬ 
ceived at the Harvard observatory, an examination of the 
photographs of that region of sky for a month previous 
