194 H, A. Newton on Shooting Stars. 
errors; yet, taken together and used with caution, it is believed 
that they may be safely employed in a first approximation, 
. Distribution vertically of the middle points of the luminous pore 
tions of the meteor-paths—From the table named, by rejecting 
the manifestly unreliable cascs, and giving weight to the other, 
the following numbers are obtained to express the relative num a 
bers of the shooting stars at different altitudes above the earth's _ 
surface. By altitude is meant the altitude of the middle point 
ef the visible part of the path expressed in kilometers. - 
Between @and 30 kil. 89 sh.stars, | Between 150 and 180 kil. 57 sh, stars, 
Ai 30 « 60 114 “ | “6 ] + 910 920 j 
eS, a er aa “; 210. 340 
ee es ee cy ae Set 3 . 
Ww SRG. © 60S 0G C8 | Above 270 kil. 1 
There is evidently a definite upper limit to the region of me 
teor-paths. Again, the best observations give few if any very 
low altitudes. The altitudes less than 30 kilometers, and those 
greater than 180, are therefore disregarded. fee 
assume that these observed paths are fair examples as to al 
titude of all visible paths, and hence that the frequency of the 
middle points of all visible paths at different altitudes above the 
earth's surface is proportional to, and may be expressed by, the 
nuinbers, viz 
From 30 kilometers to 60 by 114 
“cc 60 - “ “ 90 “ 243 
“ 90 “ “ 490 “ Q1T 
ta 120 ms “« 150 ¢: 106 
“ 150 “ “ 180° “ 57 
Representing these numbers by ¢, and the mean altitude of : 
the paths by d, we have approximately, . 
__ = 9e 
+ sae Fg 
where in the finite summation indicated by = the ccessiv@ 
values of 9 are to be taken, and x is to be successively }( 
60), $(60+90), 4(90+120 , &c. The value of d, that aa 
mean altitude of meteor paths above the earth’s surface, 18 ™ 
found to be 95:55 i 
