of Luminous Meteors. 389 



These may be nearly all divided into two great classes : — 

 1st. Blue. 



2nd. Orange, inclining more or less either to red or yellow. — 

 Under this head must be classed the red and yellow of the 

 European observations, though even then the proportional 

 amount will not equal that of the Chinese. 



A large proportion of these meteors doubtless emit all the 

 other rays of the spectrum at the same time, and in many cases 

 they are emitted so equally that no preponderating tint is 

 observed. 



Change of colour of meteor. — Another fact of interest con- 

 nected with the present subject is, the alteration that is fre- 

 quently remarked in the colour of a meteor during its passage. 

 This may be as follows : — 



From white to reddish. 

 From white to bluish. 

 According to M. Coulvier Gravier, these two changes very 

 frequently occur in meteors passing from the zenith towards the 

 horizon. M. Poey endeavours to apply to the explanation of 

 this fact the theory by which M. Doppler has sought to account 

 for the changing colours of certain stars, especially among the 

 binary systems. M. Doppler shows, on theoretical grounds, 

 that " a luminous body moving towards the observer will change 

 its colour from white in succession to the violet end of the spec- 

 trum, moving from the observer to the red/' But he requires 

 that the alteration of position of the luminous body and the ob- 

 server should bear some near comparison in speed with the velo- 

 city of light — nearly 200,000 miles per second, whereas meteors 

 fly at only about twenty miles per second on the average 1 A 

 reason that appears more possible will be presently assigned. 

 From white to orange-yellow and blue-green. 

 From white to reddish and bluish, with reddish train. 

 From yellowish white to orange-yellow and to greenish 

 white, being broken into several fragments, two of which 

 passed from white to the colour of red-hot iron. 

 From orange-yellow to gi'cen. 



From yellow and red to greenish yellow (fragments). 

 These also are given on the authority of M. Coulvier Gravier. 



From white to red. A Chinese instance. 

 From blue to red. 



From blue to green, and finally red. 

 From green to crimson. 

 From green to orange and red. 

 ' These are recorded in the British Association Catalogues, 

 having been observed by Mr. Hind, Mr. Lowe, and others. 



