A HISTORY OF SCIENCE 



morning of February 226. by star-gazers in Scotland, 

 and in America almost simultaneously. It had cer- 

 tainly not been "visible a few hours before, and it had 

 blazed up suddenly to a greater brilliancy than that of 

 a first -magnitude star. At first it was bluish -white 

 in color, indicating an extremely high temperature, but 

 it rapidly subsided in brilliancy and assum d a red 

 color as it cooled, passing thus, in the course of a few 

 days, through stages for which ordinary stars require 

 periods of many millions of years. 



The most interesting feature of the spectrum of this 

 new star was the fact that it showed both light and 

 dark lines for the same substances, the two lying some- 

 what apart. This means, being interpreted, that 

 some portions of a given substance are giving out 

 light, thus producing the bright lines of the spectrum, 

 and that other portions of the same substance are 

 stopping certain rays of transmitted light, thus pro- 

 ducing the dark lines. The space between the bright 

 and dark lines, being measured, indicated that there 

 was a differential motion between the two portions of 

 substance thus recorded of something like seven hun- 

 dred miles a second. This means, according to theory 

 and it seems hardly possible to explain it otherwise 

 that two sidereal masses, one at least of which was 

 moving at an enormous rate of speed, had collided, 

 such collision, of course, being the cause of the incan- 

 descence that made the mass suddenly visible from 

 the earth as a new star. 



New stars are by no means every -day affairs, there 

 having been but thirty-two of them recorded in the 

 world's history, and of these only two have exceeded 



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