134 RESEARCHES CONCERNING THE PERIODICAL 



inquiries. The numbers, i, 2, 3, below the letters, refer respectively to the 

 ^oup of meteors of 1833, November 12.734, 1840, August 9.456, and 1838, 

 December 7.333. 



z^ = — 0.80025 + 0.80423 x y, 



y,= + 0.62056 — 0.57905 x y^ 



z,= + 0.00336 — 0.13385 x y, 



x,= + 0.66830 — 0.45439 x y, 

 y, = + 0.74084 — 0.63354 x y^ 

 z, = — 0.00252 — 0.62622 x y, 



(17) 



x,-~- 0.98371 — 0.45439 x y, 

 y,= + 0.27412 — 0.63354 x y, 

 Zs = — 0.00445 — 0.62622 x y, 



y,= + 1.00337 ± Vlgl — 0.01874] 

 y,= + 0.77144 ± vlgl^ 0.40035] 

 5/3 = — 0.27612 ± ^[gl — 0.96660] 



§ IX. — Of THE Variations of the relative Velocity and convergent 



Point. 



The convergent point on ordinary nights, according to the observations of 

 Mr. Herrick and Mr. Forshey, varies with the point which is opposite the ob- 

 server's true direction. And if there is a similar tendency to compensation of 

 the relative velocities, then the mean relative velocity of shooting stars varies 

 with that of the observer. I have already referred to Professor Erman's 

 formulse for this variation, and have shown that the restrictions are too great, 

 from an unnecessary limit of the value of the reciprocal of y. Let us suppose 

 that the observer, in his annual and rotary motion, falls in with a group of 

 these bodies having nearly the same elements, and that he encounters the in- 

 dividuals at successive dates, t, i\ t", &c. It is manifest that if all the other 

 elements were common, the position of the plane of the orbit of the successive 

 meteors must vary with the observer's change of position, so that the elements 



