THE LIGHT OF THE STABS. 195 



Mrs Fleming on the Harvard photographs, situ- 

 ated in Aquila. 



Many theories have been advanced to account 

 for temporary stars. Flammarion has shown 

 that a body surrounded by a hydrogen atmo- 

 sphere, on grazing a dark body enveloped in 

 oxygen, would produce a tremendous explosion. 

 In 1892 Huggins suggested that the outburst 

 of Nova Aurigae was due to the near approach 

 of two bodies with large velocities, disturbances 

 of a tidal nature resulting and producing enor- 

 mous outbursts. Vogel suggested that the new 

 star was due to the encounter of a dark star 

 with a worn - out system of planets ; while 

 Lockyer believes all new stars to be due to 

 the collision of swarms of meteors. Perhaps 

 the most probable theory is that of Seeliger, 

 which attributes these outbursts to the move- 

 ment of a dark body through nebulous matter, 

 which is extensively diffused throughout space. 

 This theory explains the changes in the spectra 

 as well as the revivals of brightness which 

 characterised Nova Aurigse and the fluctations 

 of Nova Persei. In a paper read to the Royal 

 Society of Edinburgh in November 1904, the 

 German astronomer, Jacobus Halm, of the Royal 

 Observatory, Edinburgh, extended and developed 

 Seeliger's theory, showing also that the necessary 



