148 On the Meteors of 13th 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. 
A | D t B 
Let A BC (fig. 3) represent the vault of the sky, the center of 
which, D, being the place of thespectator. 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’; anda body descending 
3,3, would appear to describe the longer arc 3,3’. 
By considering thus, the manner in which the ares 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 ares, and move slower, while 
those which were further from the same axis, would appear to de- 
scribe longer ares, 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, JMe- 
teorological Essays, p. 160. 
