H. A. Newton on Shooting Stars. 205 
And as the apparent path produced backward cuts 
this point, it will, if produced forward, cut the ecliptic below 
_ the horizon 
We have thus a simple means of determining whether the 
sporadic meteors come exclusively, or even largely, from a disk 
_ ora lenticular shaped group about the sun, like that which the 
_ todiacal light is often supposed to indicate. 
_ If the third supposition is true, the mean velocity of the 
_ Ineteors is a function of the numbers of shooting stars in the 
- different hours of the night. For, if the velocity is very small, 
few would be scen in the evening, while if it is very large, there 
should be nearly as many in the evening as in the morning. 
Velocity being v, if N, represents the numbers of those whose 
_ S0solute motions in a given period are from the visible celestial 
_emisphere, n the whole number that should come from all parts 
ofthe celestial sphere, and 6 the distance from the zenith to that 
_ point of the heavens to which the earth is moving, then we find 
_ *lieen these quantities the equation, 
o— 
n v 
N =F(} +08 «), 
(tater we have cos «= cosZcosh. This will correspond to 
oe Mean of the year. Computing now the values of N,~n, on 
€n v'= v we have 
arth. When v'= v/2 we have parabolic orbits. 
After reading this memoir, I found that Mr. A. S. Herschel had obtained the 
Au Jour. Sci.—Szconp Serres, Vou. XXXIX, No. 116.—Marcu, 1865. 
