METEORS OF AUGUST AND NOVEMBER. 95 



the theoretic convergent point, if well observed, would, like those of the single 

 relative velocities from the observer's true velocity, afford us some clue towards 

 the discovery of the mean true velocities of shooting stars seen on ordinary 

 nights. The fact that Messrs. Fitch and Herrick detected the existence of 

 this actual relative convergent point, conformable to the theoretic, leads to a 

 conclusion similar to that derived from the table of relative velocities; namely, 

 that the true velocity of the meteors is small compared with that of the ob- 

 server, whence the greater prevalence of the theoretic convergent point. It is 

 probable, then, that this tendency of a part of the meteors, on ordinary nights, 

 towards the vicinity of the point opposite to the observer's direction of motion, 

 continues throughout the year, and that on each night another portion of the 

 meteors appears to be non-conformable^ or sporadic, as they are termed by Olbers 

 and Quetelet. Hence we infer that convergent meteors, so called on ordinary 

 nights, must be those which move with small, and sporadic meteors those which 

 move with greater true velocity. This circumstance has been noticed with 

 respect to their relative angular velocities by Mr. Dutton.^^ A consideration of 

 the circumstances connected with the elements of elliptic motion of these aste- 

 roids leads to a classification of the orbits of the cojivergent and sporadic meteors 

 seen on common nights. The former could not have the prevalent character of 

 convergency towards the point opposite to the observer's direction of motion, 

 without having their true velocity small. Then they must have their perihelia 

 near the sun, perhaps inferior to Mercury, and must be near their aphelia, 

 and have, therefore, pretty eccentric orbits, in order to reach the earth in their 

 aphelia. The sporadic meteors may be justly considered as a class of asteroids 

 superior to the convergent meteors, whether having their perihelia near the 

 sun, and being very eccentric, with aphelia far superior to that of the 

 earth, or having their perihelia not much inferior to that of the earth. In 

 each of the respective cases they must have great true velocities, and, moving 

 in all varieties of true direction, the average deflection of their relative direc- 

 tions from the point opposite the observer's direction is so great that they are 

 called non-conformable or sporadic. It will be shown, in the sequel, that the 

 conclusion drawn from the table of observed relative velocities, as well as from 

 the existence of a convergent point, on common nights, opposite to the ob- 

 server's true direction, namely, that a large portion of meteors seen on ordi- 



3' Sill. XXXV. p. 172. 



