148 



On the Meteors of ISth November, 1833. 



ing through the eye of the spectator; and the intersection of such 

 planes, passing through the eye of different spectators, must be straight 

 lines.* The lines of direction are inferred to have been parallel, on 

 account of their apparent radiation from one point, that being the van- 

 ishing point of parallel lines, upon well known principles of perspec- 

 tive. Some idea of the manner of falling, and of the cause of appa- 

 rent radiation, may be gathered from the annexed diegram. 



Fig. 3. 



\ 



Let ABC (fig. 3) represent the vault of the sky, the center of 

 which, D, being the place of the spectator. Let 1.2.3. &c, repre- 

 sent parallel lines directed towards the earth. A luminous body de- 

 scending through the line DE, coincident with the axis of vision, 

 would appear stationary all the while at 1'; a body descending 2,2; 

 would appear to describe the short arc 2',2'; and a body descending 

 3,3, would appear to describe the longer arc 3,3'. 



By considering thus, the manner in which the arcs described on 

 the celestial vault would appear, according as the meteor was near- 

 er to the axis of vision, or more remote from it, we shall arrive at 

 the following conclusions ; that those meteors which fell nearer to the 

 axis of vision, would describe shorter arcs, and move slower, while 

 those which were further from the same axis, would appear to de- 

 scribe longer arcs, and to move with greater velocity; that the me- 

 teors would all seem to radiate from a common center, namely, the 

 point where the axis of vision met the celestial vault ; and that if 



* See a familiar illustration of this subject in Dalton on the Aurora Borealis, Me 

 teorological Essays, p. 160. 



